Patent Publication Number: US-10767346-B2

Title: Work machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U. S. C. § 119 to Japanese Patent Application No. 2018-137186, filed Jul. 20, 2018. The contents of this application are incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a work machine. 
     Discussion of the Background 
     The work machine disclosed in JP 2009-287281 A has been known. 
     The work machine disclosed in JP 2009-287281 A includes hydraulic actuators (bucket cylinder and boom cylinder) configured to be driven by hydraulic oil, a plurality of control valves (work control valves) configured to control the hydraulic actuators, a plurality of pilot valves (work operation lever) configured to adjust the hydraulic oil serving as pilot oil, a plurality of first pipe members (work pilot hoses) respectively coupled to the plurality of pilot valves and configured to allow the pilot oil output from the plurality of pilot valves to flow, a plurality of second pipe members (work pilot hoses) respectively coupled to pressure receivers of the plurality of control valves, and a relay member coupling the plurality of first pipe members and the plurality of second pipe members, respectively. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a work machine includes a hydraulic actuator, a control valve, a first pilot oil supply pipe, a first pilot valve, a drain pipe, and a heat exchanger. The hydraulic actuator is configured to be driven via hydraulic oil. The control valve has a first pilot port and is connected to the hydraulic actuator to control the hydraulic actuator. The hydraulic actuator is configured to move in a first mode when a first pilot pressure is applied to the first pilot port. The first pilot valve is connected to the first pilot port of the control valve via the first pilot oil supply pipe to control applying the first pilot pressure to the first pilot port. The hydraulic oil is configured to be drained via the drain pipe. The drain pipe and the first pilot oil supply pipe are provided in the heat exchanger to exchange heat between the hydraulic oil in the drain pipe and the hydraulic oil in the first pilot oil supply pipe via the heat exchanger. 
     According to another aspect of the present invention, a work machine includes a hydraulic pump, a hydraulic actuator, a control valve, a first pilot oil supply pipe, an additional oil supply pipe, a first pilot valve, an additional drain pipe, and a heat exchanger. The hydraulic pump is configured to supply hydraulic oil. The hydraulic actuator is configured to be driven via the hydraulic oil. The control valve has a first pilot port and is connected to the hydraulic actuator to control the hydraulic actuator. The hydraulic actuator is configured to move in a first mode when a first pilot pressure is applied to the first pilot port. The first pilot valve is connected to the hydraulic pump via the additional oil supply pipe to receive the hydraulic oil and is connected to the first pilot port of the control valve via the first pilot oil supply pipe to control applying the first pilot pressure to the first pilot port. The additional drain pipe is connected to the additional oil supply pipe. The hydraulic oil is configured to be drained via the additional drain pipe. The additional drain pipe and the first pilot oil supply pipe are provided in the heat exchanger to exchange heat between the hydraulic oil in the additional drain pipe and the hydraulic oil in the first pilot oil supply pipe via the heat exchanger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. 
         FIG. 1  is a schematic diagram of a travel-relating hydraulic system of a work machine. 
         FIG. 2A  is a schematic diagram of a work-relating hydraulic system of the work machine. 
         FIG. 2B  is an enlarged view of a hydraulic system around a relay member. 
         FIG. 3  is a front view illustrating a machine body and the relay member, for example. 
         FIG. 4  is an enlarged front view illustrating the machine body, a plurality of first pipe members, a plurality of second pipe members, a plurality of third pipe members, a fourth pipe member, a first drain pipe member, a second drain pipe member, and the relay member, for example. 
         FIG. 5A  is a left-front perspective view illustrating the relay member. 
         FIG. 5B  is a front cross-sectional view illustrating the relay member. 
         FIG. 5C  is a left-side cross-sectional view illustrating the relay member. 
         FIG. 6A  is a left-front perspective view illustrating a relay member according to a modification example. 
         FIG. 6B  is a front view illustrating the relay member according to the modification example. 
         FIG. 6C  is a left-side cross-sectional view illustrating the relay member according to the modification example. 
         FIG. 7A  is a left-front perspective view illustrating a relay member according to a modification example. 
         FIG. 7B  is a front view illustrating the relay member according to the modification example. 
         FIG. 8A  is a front view illustrating a relay member according to a modification example. 
         FIG. 8B  is a left-side cross-sectional view illustrating the relay member according to the modification example. 
         FIG. 9A  is an enlarged view of a hydraulic system around a brake switching valve according to a modification example. 
         FIG. 9B  is an enlarged view of a hydraulic system around a relay member according to the modification example. 
         FIG. 9C  is a front view illustrating the relay member according to the modification example. 
         FIG. 9D  is a left-side cross-sectional view illustrating the relay member according to the modification example. 
         FIG. 10  is a left side view of the work machine. 
         FIG. 11A  illustrates an additional modification with respect to the example shown in  FIG. 6A . 
         FIG. 11B  illustrates an additional modification example with respect to the example shown in  FIG. 6B . 
         FIG. 11C  illustrates an additional modification example with respect to the example shown in  FIG. 6C . 
         FIG. 12A  illustrates an additional modification example with respect to the example shown in  FIG. 7A . 
         FIG. 12B  illustrates an additional modification example with respect to the example shown in  FIG. 7B . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. 
     In the work machine in JP 2009-287281 A, the plurality of first pipe members and the plurality of second pipe members are coupled via the relay member. The first pipe members and the second pipe members can thus be easily arranged. A time for attaching the first pipe members and the second pipe members can therefore be shortened, reducing a cost for producing the work machine. 
     However, when the work machine in JP 2009-287281 A is used and started under a low temperature condition, i.e., when the work machine is used and started in a cold region, for example, a temperature of the pilot oil is low, and thus viscosity of the hydraulic oil is high. The work machine thus requires warming up to warm up the pilot oil. 
     In view of the problem observed in the conventional techniques, the present invention has an object to improve ease of start-up of a work machine even under a low temperature condition by allowing pilot oil to exchange heat inside a relay member. 
     An embodiment of the present invention will now be described herein with reference to the drawings. 
       FIG. 10  illustrates a side view of a work machine  1  according to the present invention.  FIG. 10  illustrates a compact track loader as an example of the work machine  1 . However, the work machine  1  according to the present invention is not limited to a compact track loader. The work machine  1  may be another type such as skid-steer loader. 
     As illustrated in  FIG. 10 , the work machine  1  includes a machine body (vehicle body)  2 , a cabin  3 , a work device  4 , and traveling devices  5 . The cabin  3  is mounted on a front side of the machine body  2 . A driver&#39;s seat  6  is provided inside the cabin  3 . In the embodiment of the present invention, it is assumed that a front side (left side in  FIG. 10 ) of a driver sitting on the driver&#39;s seat  6  of the work machine  1  is a forward direction, a back side (right side in  FIG. 10 ) of the driver is a backward direction, a left side (near side in  FIG. 10 ) of the driver is a leftward direction, and a right side (far side in  FIG. 10 ) of the driver is a rightward direction. A horizontal direction orthogonal to a front-rear direction will be referred to as a width direction in the following description. 
     Furthermore, it is assumed that a rightward or leftward direction from a central part of the machine body  2  will be referred to as a machine body outward direction. In other words, the machine body outward direction denotes the width direction that is a direction away from the machine body  2 . Furthermore, it is assumed that a direction opposite to the machine body outward direction will be referred to as a machine body inward direction. In other words, the machine body inward direction is a direction toward the machine body  2  along the width direction. In  FIG. 10 , an arrow A 1  indicates the forward direction, and an arrow A 2  indicates the backward direction. 
     A driver&#39;s exit (not illustrated) for a driver getting on and off is provided on a front surface of the cabin  3 . This driver&#39;s exit can be opened and closed by a transparent front panel (not illustrated). This front panel can be opened and closed from an outer side of the cabin  3  (cabin exterior) and an inner side (cabin interior). 
     As illustrated in  FIG. 10 , the work device  4  includes booms  58 , a work tool  59 , lift links  60 , control links  61 , boom cylinders  62 , and bucket cylinders  63 . 
     The booms  58  are provided to be swingable in an upper-lower direction on a right side and a left side of the cabin  3 . The work tool  59  is a bucket, for example. The bucket  59  is provided to be swingable in the upper-lower direction on leading end parts (front end parts) of the booms  58 . The lift links  60  and the control links  61  support base parts (back parts) of the booms  58  to allow the booms  58  to be swingable in the upper-lower direction. The boom cylinders  62  are hydraulic actuators configured to extend and contract to lift up and down the booms  58 . The bucket cylinders  63  are hydraulic actuators configured to extend and contract to allow the bucket  59  to swing. 
     Front parts of the booms  58  on the left side and the right side are coupled with each other through a curved and forked coupling pipe. The base parts (back parts) of the booms  58  are coupled with each other through a circular coupling pipe. 
     The lift links  60 , the control links  61 , and the boom cylinders  62  are provided on a left side and a right side of the machine body  2  to correspond to the booms  58  on the left side and the right side. 
     The lift links  60  are respectively vertically provided on the back parts of the base parts of the booms  58 . Upper parts (one end sides) of the lift links  60  are pivoted rotatably about a horizontal axis closer to the back parts of the base parts of the booms  58  through a pivotal shaft  26  (first pivotal shaft). Lower parts (other end sides) of the lift links  60  are pivoted rotatably about the horizontal axis closer to a back part of the machine body  2  through a pivotal shaft  27  (second pivotal shaft). The second pivotal shaft  27  is provided below the first pivotal shaft  26 . 
     Upper parts of the boom cylinders  62  are pivoted rotatably about the horizontal axis through a pivotal shaft  28  (third pivotal shaft). The third pivotal shaft  28  is provided on the front parts of the base parts of the booms  58 . Lower parts of the boom cylinders  62  are pivoted rotatably about the horizontal axis through a pivotal shaft  29  (fourth pivotal shaft). The fourth pivotal shaft  29  is provided closer to a lower part of the back part of the machine body  2  and below the third pivotal shaft  28 . 
     As illustrated in  FIG. 10 , the control links  61  are respectively provided in front of the lift links  60 . Ends of the control links  61  are pivoted rotatably about the horizontal axis through a pivotal shaft  30  (fifth pivotal shaft). The fifth pivotal shaft  30  is provided on the machine body  2  at positions corresponding to front sides of the lift links  60 . Other ends of the control links  61  are pivoted rotatably about the horizontal axis through a pivotal shaft  31  (sixth pivotal shaft). The sixth pivotal shaft  31  is provided, on the booms  58 , in front of the second pivotal shaft  27  and above the second pivotal shaft  27 . 
     As the boom cylinders  62  extend and contract, while the base parts of the booms  58  are supported by the lift links  60  and the control links  61 , the booms  58  swing about the first pivotal shaft  26  in the upper-lower direction. The leading end parts of the booms  58  thus move up and down. As the booms  58  swing in the upper-lower direction, the control links  61  swing about the fifth pivotal shaft  30  in the upper-lower direction. As the control links  61  swing in the upper-lower direction, the lift links  60  swing about the second pivotal shaft  27  in the front-rear direction. 
     Instead of the bucket  59 , another work tool is attachable to the front parts of the booms  58 . Examples of the other work tool include attachments (auxiliary attachments) such as a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet folk, a sweeper, a mower, and a snow blower. 
     As illustrated in  FIG. 10 , a coupling member  50  is provided at the front part of the left side one of the booms  58 . The coupling member  50  is a device configured to couple a hydraulic instrument provided on an auxiliary attachment and pipe members such as pipes and hoses provided on the booms  58 . 
     The bucket cylinders  63  are respectively arranged closer to front parts of the booms  58 . As the bucket cylinders  63  extend and contract, the bucket  59  swings. 
     As illustrated in  FIG. 10 , crawler type traveling devices are adopted as the traveling devices  5  in the present embodiment. The traveling devices  5  are provided on the left side and the right side of the machine body  2 . The traveling devices  5  may be wheel type traveling devices. 
     Next, a hydraulic system of the work machine  1  according to the present invention will be described. 
     As illustrated in  FIGS. 1, 2A, and 2B , the hydraulic system can be roughly divided into a travel-relating hydraulic system  40 A and a work-relating hydraulic system  40 B. First, the travel-relating hydraulic system  40 A will be described. 
     As illustrated in  FIG. 1 , the travel-relating hydraulic system  40 A is a system configured to mainly drive travel motors  55 . 
     The travel motors  55  include a left travel motor device (first travel motor device)  55 L and a right travel motor device (second travel motor device)  55 R. As illustrated in  FIG. 1 , the travel-relating hydraulic system  40 A includes a first hydraulic pump (hydraulic pump) P 1 , a brake switching valve  151 , a brake mechanism  152 , a direction switching valve  153 , and a hydraulic device  154 . 
     The first hydraulic pump P 1  is a pump configured to be driven by power of a drive device  73 , and is formed based on a fixed-displacement type gear pump. The first hydraulic pump P 1  is configured to supply hydraulic oil stored in a hydraulic oil tank  84 . In particular, the first hydraulic pump P 1  drains the hydraulic oil mainly used for control. For convenience of description, the hydraulic oil drained from the first hydraulic pump P 1  and used for control is also referred to as pilot oil, and pressure of the pilot oil is also referred to as pilot pressure. 
     On a drain side of the first hydraulic pump P 1 , a drain oil path  140  configured to allow the hydraulic oil (the pilot oil) to flow is provided. The drain oil path  140  is coupled with a plurality of switching valves. The plurality of switching valves include the brake switching valve  151 , the direction switching valve  153 , and a hydraulic lock switching valve  155 . The drain oil path  140  is provided with a charge oil path  141  bifurcated from the drain oil path  140 . The charge oil path  141  is coupled to the hydraulic device  154 . 
     The brake switching valve  151  is coupled to a drain side of the drain oil path  140 , from which the hydraulic oil is drained. The brake switching valve  151  is a direction switching valve (electromagnetic valve) configured to allow the brake mechanism  152  to perform a brake operation and a brake releasing operation, as well as is a two-position switching valve configured to switch, through excitation, between a first position  151   a  and a second position  151   b . The brake switching valve  151  is to be switched with an operation member, for example (not illustrated). 
     The brake mechanism  152  includes a first brake mechanism  152 L configured to perform a brake control on one of the traveling devices  5 , which is provided on the left side, and a second brake mechanism  152 R configured to perform a brake control on another one of the traveling devices  5 , which is provided on the right side. The first brake mechanism  152 L and the second brake mechanism  152 R are coupled to the brake switching valve  151  via an oil path  145 . 
     The first brake mechanism  152 L and the second brake mechanism  152 R change respective operation states in accordance with the pressure of the pilot oil (hydraulic oil) to control how degree the traveling devices  5  are braked. Depending on how much the first hydraulic pump P 1  drains the pilot oil (hydraulic oil), the first brake mechanism  152 L and the second brake mechanism  152 R respectively change to an operation state for braking the travel motors  55  or a non-operation state for releasing braking. 
     When the brake switching valve  151  is put into the first position  151   a , the hydraulic oil drains from a section, between the brake switching valve  151  and the brake mechanism  152 , of the oil path  145 . The brake mechanism  152  can therefore perform braking. When the brake switching valve  151  is put into the second position  151   b , the brake mechanism  152  can release braking. The brake mechanism  152  may release braking when the brake switching valve  151  is put into the first position  151   a . The brake mechanism  152  may perform braking when the brake switching valve  151  is put into the second position  151   b.    
     The direction switching valve  153  is an electromagnetic valve configured to change rotation of the first travel motor device  55 L and the second travel motor device  55 R, and is a two-position switching valve configured to switch, through excitation, between a first position  153   a  and a second position  153   b . The direction switching valve  153  is to be switched with an operation member, for example (not illustrated). The direction switching valve  153  may not be a two-position switching valve, but may be a proportional valve configured to adjust an amount of the hydraulic oil to be drained. 
     The first travel motor device  55 L is a motor configured to transmit power to a drive shaft of one of the traveling devices  5 , which is provided on the left side of the machine body  2 . The second travel motor device  55 R is a motor configured to transmit power to a drive shaft of another one of the traveling devices  5 , which is provided on the right side of the machine body  2 . The second travel motor device  55 R operates in a similar manner to the first travel motor device  55 L. The second travel motor device  55 R is similar in configuration and actuation to the first travel motor device  55 L, and thus description for the second travel motor device  55 R will be omitted. 
     The first travel motor device  55 L includes an HST motor  156 , a swash plate switching cylinder  157 , and a travel control valve (hydraulic switching valve)  158 A. The HST motor  156  is a swash-plate variable-displacement axial motor capable of changing a vehicle speed (rotation) to a first speed or a second speed. 
     The swash plate switching cylinder  157  is a cylinder configured to change, through extension and contraction, an angle of a swash plate of the HST motor  156 . The travel control valve  158 A is a valve configured to allow the swash plate switching cylinder  157  to extend and contract toward a side or another side, and is a two-position switching valve configured to switch between a first position  158   a  and a second position  158   b . The travel control valve  158 A is to be switched by the direction switching valve  153  lying upstream of and coupled to the travel control valve  158 A. Specifically, the direction switching valve  153  and the travel control valve  158 A are coupled with each other via an oil path  142 . The travel control valve  158 A is to be thus switched by the hydraulic oil flowing into the oil path  142 . 
     With the first travel motor device  55 L described above, the pilot oil drains from a section between the direction switching valve  153  and the travel control valve  158 A when the operation member is operated to put the direction switching valve  153  into the first position  153   a . The travel control valve  158 A is thus put into the first position  158   a . As a result, the swash plate switching cylinder  157  contracts. The HST motor  156  is then put into a state of the first speed. When the operation member is operated to put the direction switching valve  153  into the second position  153   b , the pilot oil is supplied, via the direction switching valve  153 , to the travel control valve  158 A. The travel control valve  158 A is thus put into the second position  158   b . As a result, the swash plate switching cylinder  157  extends. The HST motor  156  is then put into a state of the second speed. 
     As illustrated in  FIGS. 1 and 2A , the hydraulic lock switching valve  155  is a two-position switching valve switchable between a first position  155   a  and a second position  155   b . The hydraulic lock switching valve  155  is coupled to an oil path  143  coupled to pilot valves  185 A,  185 B,  185 C, and  185 D. When the hydraulic lock switching valve  155  is at the first position  155   a , the hydraulic oil (pilot oil) in the oil path  143  drains to a drain part such as the hydraulic oil tank  84 . No pilot oil is therefore supplied to the pilot valves  185 A,  185 B,  185 C, and  185 D. When the hydraulic lock switching valve  155  is at the second position  155   b , the pilot oil in the drain oil path  140  is supplied to the oil path  143 . The pilot oil in the oil path  143  can therefore flow into the pilot valves  185 A,  185 B,  185 C, and  185 D. 
     The hydraulic system of the work machine  1  is coupled with a warming-up oil path  144 . The warming-up oil path  144  is an oil path configured to allow the pilot oil to flow from the plurality of switching valves (the brake switching valve  151 , the direction switching valve  153 , and the hydraulic lock switching valve  155 ) to the drain part such as the hydraulic oil tank  84  to perform warming up. 
     For example, the warming-up oil path  144  is coupled to drain ports of the plurality of switching valves (the brake switching valve  151 , the direction switching valve  153 , and the hydraulic lock switching valve  155 ). That is, when the brake switching valve  151  is at the first position  151   a , the hydraulic oil drains from a section, between the brake switching valve  151  and the brake mechanism  152 , of the oil path  145  to the warming-up oil path  144 . When the direction switching valve  153  is at the first position  153   a , the pilot oil in the oil path  142  drains to the warming-up oil path  144 . When the hydraulic lock switching valve  155  is at the first position  155   a , the pilot oil in the oil path  143  drains to the warming-up oil path  144 . The warming-up oil path  144  is coupled to a drain oil path  147  configured to drain the hydraulic oil. 
     The hydraulic device  154  is a device configured to drive the first travel motor device  55 L and the second travel motor device  55 R, and includes a drive circuit (left drive circuit)  154 L configured to drive the first travel motor device  55 L and a drive circuit (right drive circuit)  154 R configured to drive the second travel motor device  55 R. 
     The drive circuits  154 L and  154 R each include an HST pump (a travel hydraulic pump)  163 , speed-change oil paths  167   h  and  167   i , and a second charge oil path  167   j . The speed-change oil paths  167   h  and  167   i  are oil paths respectively coupling the HST pumps  163  and the HST motors  156 . The second charge oil path  167   j  is an oil path coupled to the speed-change oil paths  167   h  and  167   i  to supply the hydraulic oil from the first hydraulic pump P 1  to the speed-change oil paths  167   h  and  167   i.    
     The HST pump  163  is a swash-plate variable-displacement axial pump configured to be driven by power of the drive device  73 . The HST pump  163  includes a pressure receiver  163   a  for forward movement and a pressure receiver  163   b  for backward movement. The pressure receivers  163   a  and  163   b  are each configured to receive the pilot pressure. The pilot pressure acting onto the pressure receiver  163   a  or  163   b  changes an angle of the swash plate. Changing the angle of the swash plate can change an output (an amount of the hydraulic oil to be supplied) of the HST pump  163  and a direction of the hydraulic oil to be supplied. 
     A travel operation device  160  changes the outputs of the HST pumps  163  and the direction of the hydraulic oil to be supplied. Specifically, a travel lever  164  included in the travel operation device  160  can be used to change the outputs of the HST pumps  163  and the direction of the hydraulic oil to be supplied. The travel operation device  160  will be described herein in detail. 
     As illustrated in  FIG. 1 , an oil path  146  bifurcated from the drain oil path  140  is coupled to the travel operation device  160 . The travel operation device  160  includes an operation valve  165 A for forward traveling, an operation valve  165 B for backward traveling, an operation valve  165 C for right turning, an operation valve  165 D for left turning, and the travel lever  164 . The travel operation device  160  further includes first to fourth shuttle valves  165   a ,  165   b ,  165   c , and  165   d . The operation valves  165 A,  165 B,  165 C, and  165 D are operated with a common lever, i.e., the travel lever  164 . In accordance with an operation of the travel lever  164  (operation member), the operation valves  165 A,  165 B,  165 C, and  165 D change the pressure of the hydraulic oil and supply the hydraulic oil at the pressure being changed to the pressure receivers  163   a  and  163   b  of the HST pumps  163 . In the embodiment, the travel lever  164  is used to operate the operation valves  165 A,  165 B,  165 C, and  165 D. However, a plurality of the travel levers  164  may be used. For example, a first travel lever may be arranged on one side (left side) of the driver&#39;s seat  6 , whereas a second travel lever may be arranged on another side. The two travel levers may be used to operate the operation valves  165 A,  165 B,  165 C, and  165 D. 
     The operation valves  165 A,  165 B,  165 C, and  165 D respectively include drain ports (ports). As illustrated in  FIG. 1 , the drain ports are coupled to an oil path  175 . As illustrated in  FIG. 2A , the oil path  175  is coupled to the drain oil path  147  configured to drain the hydraulic oil. 
     The travel lever  164  can be tilted, from a neutral position, in forward and backward directions, width directions orthogonal to the forward and backward directions, and diagonal directions. When the travel lever  164  is tilted, the operation valves  165 A,  165 B,  165 C, and  165 D of the travel operation device  160  are operated. As a result, the pilot pressure proportional to an amount of the operation of the travel lever  164  from the neutral position is output from secondary-side ports of the operation valves  165 A,  165 B,  165 C, and  165 D. 
     When the travel lever  164  is tilted forward, the operation valve  165 A for forward traveling is operated. The pilot pressure is thus output from the operation valve  165 A. The pilot pressure acts from the first shuttle valve  165   a , via an oil path  171 , onto the pressure receiver  163   a  for forward movement of the left drive circuit  154 L, as well as acts from the second shuttle valve  165   b , via an oil path  172 , onto the pressure receiver  163   a  for forward movement of the right drive circuit  154 R. Output shafts of the HST motors  156  therefore normally rotate (forward-rotate) at a speed proportional to an amount of tilt of the travel lever  164 . The work machine  1  thus moves straight forward. 
     When the travel lever  164  is tilted backward, the operation valve  165 B for backward traveling is operated. The pilot pressure is thus output from the operation valve  165 B. The pilot pressure acts from the third shuttle valve  165   c , via an oil path  174 , onto the pressure receiver  163   b  for backward movement of the left drive circuit  154 L, as well as acts from the fourth shuttle valve  165   d , via an oil path  173 , onto the pressure receiver  163   b  for backward movement of the right drive circuit  154 R. The output shafts of the HST motors  156  therefore reverse-rotate (backward-rotate) at a speed proportional to an amount of tilt of the travel lever  164 . The work machine  1  thus moves straight backward. 
     When the travel lever  164  is tilted rightward, the operation valve  165 C for right turning is operated. The pilot pressure is thus output from the operation valve  165 C. The pilot pressure acts from the first shuttle valve  165   a , via the oil path  171 , onto the pressure receiver  163   a  for forward movement of the left drive circuit  154 L, as well acts from the fourth shuttle valve  165   d , via the oil path  173 , onto the pressure receiver  163   b  for backward movement of the right drive circuit  154 R. The output shaft of the HST motor  156  on the left side therefore normally rotates, whereas the output shaft of the HST motor  156  on the right side therefore reverse-rotates. The work machine  1  thus makes a right turn. 
     When the travel lever  164  is tilted leftward, the operation valve  165 D for left turning is operated. The pilot pressure is thus output from the operation valve  165 D. The pilot pressure acts from the second shuttle valve  165   b , via the oil path  172 , onto the pressure receiver  163   a  for forward movement of the right drive circuit  154 R, as well as acts from the third shuttle valve  165   c , via the oil path  174 , onto the pressure receiver  163   b  for backward movement of the left drive circuit  154 L. The output shaft of the HST motor  156  on the right side therefore normally rotates, whereas the output shaft of the HST motor  156  on the left side therefore reverse-rotates. The work machine  1  thus makes a left turn. 
     That is, when the travel lever  164  is tilted diagonally leftward and forward, the work machine  1  moves forward and makes a left turn at a speed corresponding to an angle of tilt of the travel lever  164 . When the travel lever  164  is tilted diagonally rightward and forward, the work machine  1  moves forward and makes a right turn at a speed corresponding to an angle of tilt of the travel lever  164 . When the travel lever  164  is tilted diagonally leftward and backward, the work machine  1  moves backward and makes a left turn at a speed corresponding to an angle of tilt of the travel lever  164 . When the travel lever  164  is tilted diagonally rightward and backward, the work machine  1  moves backward and makes a right turn at a speed corresponding to an angle of tilt of the travel lever  164 . 
     Next, the work-relating hydraulic system  40 B will be described. As illustrated in  FIG. 2A , the work-relating hydraulic system  40 B is a system configured to operate the booms  58 , the bucket  59 , and an auxiliary attachment, for example, and includes a work-relating hydraulic pump (second hydraulic pump) P 2 , a plurality of control valves  180 , a third hydraulic pump P 3 , a high-flow valve  181 , and a high-flow switching valve  182 . 
     The second hydraulic pump P 2  is a pump provided at a position different from a position of the first hydraulic pump P 1 , and is formed based on a fixed-displacement type gear pump. The second hydraulic pump P 2  is configured to supply the hydraulic oil stored in the hydraulic oil tank  84 . In particular, the second hydraulic pump P 2  supplies the hydraulic oil mainly used to actuate a hydraulic actuator. The third hydraulic pump P 3  is a pump provided at a position different from the positions of the first hydraulic pump P 1  and the second hydraulic pump P 2 , and is formed based on a fixed-displacement type gear pump. 
     On a supply side of the second hydraulic pump P 2 , a main oil path (oil path)  148  is provided. The main oil path  148  is coupled with the plurality of control valves  180 . The control valves  180  are valves configured to use the pilot pressure of the pilot oil to switch a direction of the hydraulic oil to be flowed. The control valves  180  are valves configured to control a hydraulic actuator (a hydraulic instrument). The hydraulic instrument is an instrument for controlling (driving), for example, a hydraulic device such as the booms  58 , the bucket  59 , a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet folk, a sweeper, a mower, or a snow blower, and is, for example, a hydraulic cylinder or a hydraulic motor. 
     As illustrated in  FIG. 2A , the plurality of control valves  180  include a first control valve  180 A, a second control valve  180 B, and a third control valve  180 C. The first control valve  180 A is a valve configured to control the hydraulic actuators (boom cylinders)  62  configured to control the booms  58 . The second control valve  180 B is a valve configured to control the hydraulic actuators (bucket cylinders)  63  configured to control the bucket  59 . The third control valve  180 C is a valve configured to control a hydraulic instrument (hydraulic cylinder or hydraulic motor) mounted on an auxiliary attachment such as a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet folk, a sweeper, a mower, or a snow blower. 
     The first control valve  180 A and the second control valve  180 B respectively are pilot-type, directly-operated spool type three-position switching valves. The control valves each switch among a neutral position, a first position different from the neutral position, and a second position different from the neutral position and the first position. With the pilot pressure acting onto a pressure receiver  180   a  on a side and a pressure receiver  180   b  on another side, the first control valve  180 A switches among the neutral position, the first position different from the neutral position, and the second position different from the neutral position and the first position. With the pilot pressure acting onto a pressure receiver  180   c  on a side and a pressure receiver  180   d  on another side, the second control valve  180 B switches among the neutral position, the first position different from the neutral position, and the second position different from the neutral position and the first position. 
     The first control valve  180 A is coupled with the boom cylinders  62  via oil paths. The second control valve  180 B is coupled with the bucket cylinders  63  via oil paths. 
     The booms  58  and the bucket  59  can be operated with an operation lever  184  provided around the driver&#39;s seat  6 . The operation lever  184  is supported to be tiltable, from a neutral position, in the forward, backward, leftward, rightward, and diagonal directions. When the operation lever  184  is tilted, the plurality of pilot valves (operation valves)  185 A,  185 B,  185 C, and  185 D provided below the operation lever  184  can be operated. The pilot valves  185 A,  185 B,  185 C, and  185 D and the first hydraulic pump P 1  are coupled with each other via the drain oil path  140 , the hydraulic lock switching valve  155 , and the oil path  143 . The pilot valves  185 A,  185 B,  185 C, and  185 D include drain ports (ports) coupled to an oil path  195 . 
     As illustrated in  FIG. 2A , the plurality of pilot valves (operation valves)  185 A,  185 B,  185 C,  185 D and the plurality of control valves  180  are coupled with each other via a plurality of oil paths  191 ,  192 ,  193 , and  194 . Specifically, the pilot valve  185 A is coupled to the pressure receiver  180   a  of the first control valve  180 A via the oil path  191 . The pilot valve  185 B is coupled to the pressure receiver  180   b  of the first control valve  180 A via the oil path  192 . The pilot valve  185 C is coupled to the pressure receiver  180   c  of the second control valve  180 B via the oil path  193 . The pilot valve  185 D is coupled to the pressure receiver  180   d  of the second control valve  180 B via the oil path  194 . Each of the pilot valves  185 A,  185 B,  185 C, and  185 D can be set with the pressure of the hydraulic oil to be output in accordance with an operation of the operation lever  184 . In other words, the pilot valves  185 A,  185 B,  185 C, and  185 D can each adjust the hydraulic oil serving as the pilot oil. 
     More specifically, when the operation lever  184  is tilted forward, the pilot valve (operation valve)  185 A for moving-down is operated. The pilot pressure of the pilot oil to be output from the pilot valve  185 A for moving-down is thus set. The pilot pressure acts onto the pressure receiver  180   a  of the first control valve  180 A. The boom cylinders  62  contract. The booms  58  thus lower. 
     When the operation lever  184  is tilted backward, the pilot valve (operation valve)  185 B for moving-up is operated. The pilot pressure of the pilot oil to be output from the pilot valve  185 B for moving-up is thus set. The pilot pressure acts onto the pressure receiver  180   b  of the first control valve  180 A. The boom cylinders  62  extend. The booms  58  thus rise. 
     When the operation lever  184  is tilted rightward, the pilot valve (operation valve)  185 C for bucket-dump is operated. The pilot pressure of the pilot oil to be output from the pilot valve  185 C is thus set. The pilot pressure acts onto the pressure receiver  180   c  of the second control valve  180 B. The bucket cylinders  63  extend. The bucket  59  thus performs a dumping operation. 
     When the operation lever  184  is tilted leftward, the pilot valve (operation valve)  185 D for bucket-scooping is operated. The pilot pressure of the pilot oil to be output from the pilot valve  185 D is thus set. The pilot pressure acts onto the pressure receiver  180   d  of the second control valve  180 B. The bucket cylinders  63  contract. The bucket  59  thus performs a scooping operation. 
     The third control valve  180 C is a pilot-type, directly-operated spool type three-position switching valve. The third control valve  180 C switches its switching position with the pilot pressure to control a direction, an amount, and pressure of the hydraulic oil heading toward a hydraulic instrument of an auxiliary attachment. Specifically, oil paths (supply oil paths)  196  and  197  are coupled between the third control valve  180 C and the coupling member  50  coupling the hydraulic instrument. The oil path  196  is coupled with a relief path  196   a  provided with a first relief valve. The hydraulic oil is thus to be drained. The oil path  197  is coupled with a relief path  197   a  provided with a relief valve. The hydraulic oil is thus to be drained. 
     The high-flow valve  181  is a hydraulic switching valve formed based on a pilot-type two-position switching valve. The high-flow valve (hydraulic switching valve)  181  is configured to switch, with the pilot pressure, between two switching positions (a non-increment position  181   a  and a increment position  181   b ). An inlet port of the high-flow valve  181  is coupled with an oil path on a supply side of the third hydraulic pump P 3 . An outlet port of the high-flow valve  181  is coupled with an oil path (increment oil path)  198  joining the oil path  196  configured to supply the hydraulic oil to a hydraulic instrument of an auxiliary attachment. The high-flow valve  181  includes a drain port (port) coupled to the hydraulic oil tank  84 . 
     The high-flow switching valve  182  is a direction switching valve formed based on an electromagnetic type two-position switching valve coupled to the pressure receiver  181   c  of the high-flow valve  181 , and is switchable between an acting position  182   a  allowing the pilot pressure to act onto the pressure receiver  181   c  and a non-acting position  182   b  disallowing the pilot pressure to act onto the pressure receiver  181   c . The high-flow switching valve  182  includes a drain port (port) coupled to an oil path  183 . The oil path  183  is coupled to the drain oil path  147 . 
     When the high-flow switching valve  182  is put into the acting position  182   a , the pressure (pilot pressure) of the pilot oil supplied from the third hydraulic pump P 3  acts onto the pressure receiver  181   c  of the high-flow valve  181 . The high-flow valve  181  is thus put into the increment position  181   b . As a result, the oil supplied from the third hydraulic pump P 3  flows into the increment oil path  198 . The hydraulic oil in the increment oil path  198  and the hydraulic oil in the oil path  196  are added to each other. The hydraulic oil thus increases in amount. 
     When the high-flow switching valve  182  is put into the non-acting position  182   b  where the pilot pressure (set pressure) required to move a spool of the high-flow valve  181  is disallowed to act onto the pressure receiver  181   c , the pilot pressure at or above the set pressure does not act onto the pressure receiver  181   c  of the high-flow valve  181 . The high-flow valve  181  is thus put into the non-increment position  181   a  (switched to a non-increment mode). 
     As illustrated in  FIGS. 2A, 2B, 3, and 4 , the work machine  1  includes a relay member  200  (a heat exchanger  200 ) configured to relay a plurality of pipe members such as pipes and hoses when the pipe members are coupled. The relay member  200  is coupled with a plurality of first pipe members  211 . As illustrated in  FIGS. 2A and 2B , the plurality of first pipe members  211  are respectively coupled to the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D to allow the hydraulic oil output from the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D to flow. Among the plurality of first pipe members  211 , an end of a first pipe member  211   a  (a part  211   a  of a first pilot oil supply pipe) configured to allow the hydraulic oil output from the pilot valve  185 A to flow is coupled to an outlet port  185 A 1  of the pilot valve  185 A. Among the plurality of first pipe members  211 , an end of a first pipe member  211   b  (a part  211   b  of a second pilot oil supply pipe) configured to allow the hydraulic oil output from the pilot valve  185 B to flow is coupled to an outlet port  185 B 1  of the pilot valve  185 B. Among the plurality of first pipe members  211 , an end of a first pipe member  211   c  (a part  211   c  of an additional pilot oil supply pipe) configured to allow the hydraulic oil output from the pilot valve  185 C to flow is coupled to an outlet port  185 C 1  of the pilot valve  185 C. Among the plurality of first pipe members  211 , an end of a first pipe member  211   d  (a part  211   d  of another additional pilot oil supply pipe) configured to allow the hydraulic oil output from the pilot valve  185 D to flow is coupled to an outlet port  185 D 1  of the pilot valve  185 D. Other ends of the first pipe members  211   a  to  211   d  are coupled to the relay member  200 . 
     The relay member  200  is coupled with a plurality of second pipe members  212 . The plurality of second pipe members  212  are respectively coupled to the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  (a first pilot port  180   a , a second pilot port  180   b , an additional pilot port  180   c , and another additional pilot port  180   d ) of the plurality of control valves  180 A and  180 B. Among the plurality of second pipe members  212 , an end of a second pipe member  212   a  (a part  212   a  of the first pilot port supply pipe) configured to allow the hydraulic oil to flow to the pressure receiver  180   a  is coupled to the pressure receiver  180   a . Among the plurality of second pipe members  212 , an end of a second pipe member  212   b  (a part  212   b  of the second pilot oil supply pipe) configured to allow the hydraulic oil to flow to the pressure receiver  180   b  is coupled to the pressure receiver  180   b . Among the plurality of second pipe members  212 , an end of a second pipe member  212   c  (a part  212   c  of the additional pilot oil supply pipe) configured to allow the hydraulic oil to flow to the pressure receiver  180   c  is coupled to the pressure receiver  180   c . Among the plurality of second pipe members  212 , an end of a second pipe member  212   d  (a part  212   d  of the other additional pilot oil supply pipe) configured to allow the hydraulic oil to flow to the pressure receiver  180   d  is coupled to the pressure receiver  180   d . Other ends of the second pipe member  212   a  to  212   d  are respectively coupled to the relay member  200 . 
     The relay member  200  is further coupled with a third pipe member  213 , a fourth pipe member  214 , a plurality of first drain pipe members  215 , and a second drain pipe member  216 . The third pipe member  213  allows the hydraulic oil supplied from the first hydraulic pump P 1  to flow. Specifically, an end of the third pipe member  213  is coupled to an outlet port of the hydraulic lock switching valve  155 , and another end is coupled to the relay member  200 . 
     The fourth pipe member  214  is a pipe member configured to supply the pilot oil flowing in the third pipe member  213  to the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D, and is a pipe member distinct from the first pipe member  211 . The fourth pipe member  214  bifurcates at a middle position. Bifurcated ends are respectively coupled to an inlet port  185 A 2  of the pilot valves  185 A and  185 B and an inlet port  185 C 2  of the pilot valves  185 C and  185 D. Another end of the fourth pipe member  214  is coupled to the relay member  200 . 
     The plurality of first drain pipe members  215  are configured to drain the hydraulic oil. Specifically, the plurality of first drain pipe members  215  include a first drain pipe member  215   a  configured to drain the hydraulic oil drained from the travel operation device  160 , and a first drain pipe member  215   b  coupled to a drain port  185 A 3  configured to drain the hydraulic oil drained from the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D. The plurality of first drain pipe members  215  further include a first drain pipe member  215   c  configured to drain the pilot oil in the warming-up oil path  144 , and a first drain pipe member  215   d  configured to drain the pilot oil drained from the high-flow valve  181  and the high-flow switching valve  182 . The plurality of first drain pipe members  215  (the first drain pipe members  215   a  to  215   d ) are coupled to the relay member  200 . 
     The second drain pipe member  216  is configured to return the pilot oil (hydraulic oil) flowing in the plurality of first drain pipe members  215  to the drain part such as the hydraulic oil tank  84 . An end of the second drain pipe member  216  is coupled to the drain part. Another end is coupled to the relay member  200 . 
     The relay member  200  will be described herein in detail with mainly reference to  FIGS. 3 to 5C .  FIG. 5A  is a left-front perspective view of the relay member  200 .  FIG. 5B  is a front cross-sectional view of the relay member  200 .  FIG. 5C  is a left-side cross-sectional view of the relay member  200 . In each of  FIGS. 5A, 5B, and 5C , the arrow A 1  indicates the forward direction, the arrow A 2  indicates the backward direction, an arrow B 1  indicates the leftward direction, and an arrow B 2  indicates the rightward direction. As illustrated in  FIGS. 5 and 6 , the relay member  200  is attached to an upper frame  12 . Specifically, the relay member  200  is arranged on a right side of a front face of the upper frame  12 . The relay member  200  is secured to the front face of the upper frame  12  with fastening members  200 A such as bolts. The relay member  200  is made of a metallic material with superior thermal conductivity, such as aluminum and steel. The relay member  200  includes a main body  201 , a plurality of inlet ports  202 , a plurality of outlet ports  203 , a first supply port  204 , a second supply port  205 , and a plurality of first drain ports  206 . 
     As illustrated in  FIGS. 3 to 5C , the main body  201  of the relay member  200  is a joint member having a substantially rectangular shape where a length in the upper-lower direction is longer than each of a length in the front-rear direction and a length of the width direction. 
     The plurality of inlet ports  202  are respectively provided on a side (right side) in the width direction of the main body  201 . The plurality of inlet ports  202  are provided on the main body  201  to align in the upper-lower direction. The plurality of inlet ports  202  are respectively coupled with the plurality of first pipe members  211 . Specifically, the plurality of inlet ports  202  include an inlet port  202   a  coupled with the first pipe member  211   a  and an inlet port  202   b  coupled with the first pipe member  211   b . The plurality of inlet ports  202  further include an inlet port  202   c  coupled with the first pipe member  211   c  and an inlet port  202   d  coupled with the first pipe member  211   d.    
     The plurality of outlet ports  203  are respectively provided on another side (left side) in the width direction of the main body  201 . The plurality of outlet ports  203  are provided on the main body  201  to align in the upper-lower direction. The plurality of outlet ports  203  are respectively coupled with the plurality of second pipe members  212 . Specifically, the plurality of outlet ports  203  include an outlet port  203   a  coupled with the second pipe member  212   a  and an outlet port  203   b  coupled with the second pipe member  212   b . The plurality of outlet ports  203  further include an outlet port  203   c  coupled with the second pipe member  212   c  and an outlet port  203   d  coupled with the second pipe member  212   d.    
     The first supply port  204  is provided on the other side (left side) in the width direction of the main body  201 . The first supply port  204  is coupled with the third pipe member  213 . The second supply port  205  is provided on the side (right side) in the width direction of the main body  201 . The second supply port  205  is coupled with the fourth pipe member  214 . 
     The plurality of first drain ports  206  are respectively provided on the side (right side) and the other side (left side) in the width direction of the main body  201 . The plurality of first drain ports  206  are respectively coupled with the plurality of first drain pipe members  215 . Specifically, the plurality of first drain ports  206  include a first drain port  206   a  coupled with the first drain pipe member  215   a , a first drain port  206   b  coupled with the first drain pipe member  215   b , a first drain port  206   c  coupled with the first drain pipe member  215   c , and a first drain port  206   d  coupled with the first drain pipe member  215   d . The second drain port  207  is provided at a lower part of the main body  201 . The second drain port  207  is coupled with the second drain pipe member  216 . 
     As illustrated in  FIGS. 5B and 5C , the relay member  200  includes a plurality of first channels  208 , a third channel  209 , and a second channel  210 . The plurality of first channels  208  are respectively configured to allow the plurality of inlet ports  202  and the plurality of outlet ports  203  to communicate with each other. The plurality of first channels  208  are oil paths formed to align in the upper-lower direction inside the main body  201 . The plurality of first channels  208  are provided to extend in the width direction. Specifically, the plurality of first channels  208  include a first channel  208   a  (a part  208   a  of the first pilot oil supply pipe) configured to allow the inlet port  202   a  and the outlet port  203   a  to communicate with each other and a first channel  208   b  (a part  208   b  of the second pilot oil supply pipe) configured to allow the inlet port  202   b  and the outlet port  203   b  to communicate with each other. The plurality of first channels  208  further include a first channel  208   c  (a part  208   c  of the additional pilot oil supply pipe) configured to allow the inlet port  202   c  and the outlet port  203   c  to communicate with each other and a first channel  208   d  (a part  208   d  of the other additional pilot oil supply pipe) configured to allow the inlet port  202   d  and the outlet port  203   d  to communicate with each other. 
     The third channel  209  is configured to allow the first supply port  204  and the second supply port  205  to communicate with each other. The third channel  209  is an oil path formed inside the main body  201 . The third channel  209  is provided to extend in the width direction. 
     The second channel  210  is configured to allow the plurality of first drain ports  206  and the second drain port  207  to communicate with each other. The second channel  210  is an oil path formed inside the main body  201 . Specifically, as illustrated in  FIG. 5C , the second channel  210  includes a channel  210   a , a channel  210   b , and a channel  210   c . The channel  210   a  is an oil path configured to allow the first drain port  206   a  and the first drain port  206   b  to communicate with each other. The channel  210   a  is formed at an upper part inside the main body  201  to extend in the width direction. The channel  210   b  is an oil path configured to allow the first drain port  206   c  and the first drain port  206   d  to communicate with each other. The channel  210   b  is formed at the lower part inside the main body  201  to extend in the width direction. The channel  210   c  is an oil path configured to allow the channel  210   a , the channel  210   b , and the second drain port  207  to communicate with each other. Specifically, the channel  210   c  is formed to extend downward from a middle part of the channel  210   a , joins the channel  210   b , and communicates with the second drain port  207 . Therefore, the second channel  210  allows the plurality of first drain ports  206  and the second drain port  207  to communicate with each other. 
     A part of the work-relating hydraulic system  40 B described above includes the plurality of first pipe members  211 , the plurality of second pipe members  212 , the plurality of third pipe members  213 , the fourth pipe member  214 , the first drain pipe member  215 , the second drain pipe member  216 , the plurality of inlet ports  202 , the plurality of outlet ports  203 , the first supply port  204 , the second supply port  205 , the plurality of first drain ports  206 , the second drain port  207 , the first channels  208 , the third channel  209 , and the second channel  210 . To describe specifically, as illustrated in  FIGS. 2A and 2B , a part of the oil path  191  includes the first pipe member  211   a , the inlet port  202   a , the first channel  208   a , the outlet port  203   a , and the second pipe member  212   a . A part of the oil path  192  includes the first pipe member  211   b , the inlet port  202   b , the first channel  208   b , the outlet port  203   b , and the second pipe member  212   b . A part of the oil path  193  includes the first pipe member  211   c , the inlet port  202   c , the first channel  208   c , the outlet port  203   c , and the second pipe member  212   c . A part of the oil path  194  includes the first pipe member  211   d , the inlet port  202   d , the first channel  208   d , the outlet port  203   d , and the second pipe member  212   d . A part of the oil path  143  includes the third pipe member  213 , the first supply port  204 , the third channel  209 , the second supply port  205 , and the fourth pipe member  214 . A part of the oil path  175  includes the first drain pipe member  215   a  and the first drain port  206   a . A part of the oil path  195  includes the first drain pipe member  215   b  and the first drain port  206   b . A part of the oil path  144  includes the first drain pipe member  215   c  and the first drain port  206   c . A part of the oil path  183  includes the first drain pipe member  215   d  and the first drain port  206   d . A part of the drain oil path  147  includes the second channel  210 , the second drain port  207 , and the second drain pipe member  216 . 
     Herein will describe, with mainly reference to  FIGS. 5A, 5B, and 5C , a position relationship among the plurality of inlet ports  202 , the plurality of outlet ports  203 , the first supply port  204 , the second supply port  205 , the plurality of first drain ports  206 , the second drain port  207 , the first channels  208 , the third channel  209 , and the second channel  210 . 
     The plurality of inlet ports  202 , the second supply port  205 , the first drain port  206   b , and the first drain port  206   d  are formed to align in the upper-lower direction on the side (right side) of the main body  201 . 
     Specifically, the plurality of inlet ports  202 , the second supply port  205 , the first drain port  206   b , and the first drain port  206   d  are arranged from the upper part on the right side of the main body  201  at predetermined intervals in an order of the first drain port  206   b , the inlet port  202   a , the inlet port  202   b , the inlet port  202   c , the inlet port  202   d , the second supply port  205 , and the first drain port  206   d.    
     On the other hand, the plurality of outlet ports  203 , the first supply port  204 , the first drain port  206   a , and the first drain port  206   c  are formed to align in the upper-lower direction on the other side (left side) of the main body  201 . Specifically, the plurality of outlet ports  203 , the first supply port  204 , the first drain port  206   a , and the first drain port  206   c  are arranged from the upper part on the left side of the main body  201  at predetermined intervals in an order of the first drain port  206   a , the outlet port  203   a , the outlet port  203   b , the outlet port  203   c , the outlet port  203   d , the first supply port  204 , and the first drain port  206   c.    
     That is, as illustrated in  FIGS. 5A and 5B , the plurality of first channels  208 , the third channel  209 , the channel  210   a , and the channel  210   b  are formed to align in the upper-lower direction inside the main body  201 . Specifically, the plurality of first channels  208 , the third channel  209 , the channel  210   a , and the channel  210   b  are arranged from the upper part inside the main body  201  at predetermined intervals in an order of the channel  210   a , the first channel  208   a , the first channel  208   b , the first channel  208   c , the first channel  208   d , the third channel  209 , and the channel  210   b . The plurality of first channels  208  are arranged to align with each other in a single column. The relay member  200  can thus be formed thinner in a direction in which the first channels  208  and the third channel  209  are orthogonal to the second channel  210 . Even when the relay member  200  is to be attached to a relatively narrower region, the relay member  200  can therefore be easily attached to the work machine  1 . 
     As illustrated in  FIG. 5C , the channel  210   c  is formed, inside the main body  201 , in front of the first channels  208 , the third channel  209 , the channel  210   a , and the channel  210   b . The second channel  210  is provided across the plurality of first channels  208  and the third channel  209 . More specifically, the second channel  210  is formed, from the upper part of the main body  201  in order, across the first channel  208   a  and the first channel  208   b , across the first channel  208   b  and the first channel  208   c , and across the first channel  208   c  and the first channel  208   d . The channel  210   c  of the second channel  210  is also formed across the first channel  208   d  and the third channel  209 . That is, when focused on how the first channels  208   a  to  208   d  are arranged, the channel  210   c  of the second channel  210  is provided to extend in an arrangement direction of the first channels  208   a  to  208   d . When focused on how the first channel  208   d  and the third channel  209  are arranged, the channel  210   c  of the second channel  210  is also provided to extend in an arrangement direction of the first channel  208   d  and the third channel  209 . 
     As illustrated in  FIG. 5B , when how the plurality of first channels  208  and the third channel  209  overlap with the channel  210   c  of the second channel  210  is viewed in a cross section, the channel  210   c  extends in a direction (upper-lower direction) orthogonal to a direction (width direction) in which the plurality of first channels  208  and the third channel  209  are provided and extended. 
     Next, how the hydraulic oil relating to the relay member  200  flows will be described with mainly reference to  FIGS. 5B and 5C . The hydraulic oil output from the pilot valve  185 A flows from the outlet port  185 A 1  of the pilot valve  185 A, via the first pipe member  211   a , into the inlet port  202   a  of the relay member  200 . The hydraulic oil flowed into the inlet port  202   a  passes through the first channel  208   a  and flows from the outlet port  203   a  into the second pipe member  212   a  (R 1 ). 
     The hydraulic oil output from the pilot valve  185 B flows from the outlet port  185 B 1  of the pilot valve  185 B, via the first pipe member  211   b , into the inlet port  202   b  of the relay member  200 . The hydraulic oil flowed into the inlet port  202   b  passes through the first channel  208   b  and flows from the outlet port  203   b  into the second pipe member  212   b  (R 2 ). 
     The hydraulic oil output from the pilot valve  185 C flows from the outlet port  185 C 1  of the pilot valve  185 C, via the first pipe member  211   c , into the inlet port  202   c  of the relay member  200 . The hydraulic oil flowed into the inlet port  202   c  passes through the first channel  208   c  and flows from the outlet port  203   c  into the second pipe member  212   c  (R 3 ). The hydraulic oil output from the pilot valve  185 D flows from the outlet port  185 D 1  of the pilot valve  185 D, via the first pipe member  211   d , into the inlet port  202   d  of the relay member  200 . The hydraulic oil flowed into the inlet port  202   d  passes through the first channel  208   d  and flows from the outlet port  203   d  into the second pipe member  212   d  (R 4 ). The hydraulic oil supplied from the first hydraulic pump P 1  flows, via the third pipe member  213 , into the first supply port  204 . The hydraulic oil flowed into the first supply port  204  passes through the third channel  209  and flows into the second supply port  205  (R 5 ). The hydraulic oil flowed into the second supply port  205  passes through the fourth pipe member  214  and flows into the inlet ports  185 A 2  and  185 C 2 . 
     The hydraulic oil drained from the travel operation device  160  flows, via the first drain pipe member  215   a , into the first drain port  206   a . The hydraulic oil flowed into the first drain port  206   a  flows into the channel  210   a  (R 6 ). The hydraulic oil drained from the pilot valves  185 A,  185 B,  185 C, and  185 D flows from the drain port  185 A 3 , via the first drain pipe member  215   b , into the first drain port  206   b . The hydraulic oil flowed into the first drain port  206   b  flows into the channel  210   a  (the second channel  210 ) (R 7 ). 
     Therefore, the hydraulic oil drained from the travel operation device  160  and the hydraulic oil drained from the pilot valves  185 A,  185 B,  185 C, and  185 D can flow into the channel  210   a  (the second channel  210 ). As illustrated in  FIG. 5C , the hydraulic oil flowed into the channel  210   a  flows into the channel  210   c  of the second channel  210  downward from the upper part of main body  201  (R 10 ) to exchange heat with the hydraulic oil flowing in the plurality of first channels  208  and the hydraulic oil flowing in the third channel  209 . Specifically, the hydraulic oil flowing in the channel  210   c  of the second channel  210  exchanges heat with, in order, the hydraulic oil flowing in the first channel  208   a , the hydraulic oil flowing in the first channel  208   b , the hydraulic oil flowing in the first channel  208   c , the hydraulic oil flowing in the first channel  208   d , and the hydraulic oil flowing in the third channel  209 . When the hydraulic oil is supplied from the pilot valves  185 A,  185 B,  185 C, and  185 D to the first channels  208 , and when the operation valves  165 A,  165 B,  165 C, and  165 D are not operated (while the travel lever  164  is at the neutral position and thus is not operated), the hydraulic oil at relatively low pressure flows into the second channel  210 . The hydraulic oil flowing in the second channel  210  and the hydraulic oil flowing in the first channels  208  can therefore exchange heat. After the work machine  1  is started, the hydraulic oil flows at a relatively lesser amount into the oil path configured to drain the hydraulic oil than an amount of the hydraulic oil flowing in the oil path configured to allow the hydraulic oil to flow from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180 . Even though a further time is required to warm up the oil paths, the hydraulic oil flowing in the first channels  208  and the hydraulic oil flowing in the second channel  210  can exchange heat. The hydraulic oil flowing from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180  can therefore warm up the hydraulic oil in the oil path configured to drain the hydraulic oil. The hydraulic oil supplied from the hydraulic pump P 1  is relatively higher in temperature than the hydraulic oil flowing in the oil path configured to allow the hydraulic oil to flow from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180 . Efficiency in exchanging heat among the first channels  208 , the third channel  209 , and the second channel  210  can therefore be further increased. The relay member  200  is made of a metallic material. The metallic material normally has higher heat conductivity. The hydraulic oil flowing in the second channel  210  can therefore be efficiently heated. 
     The hydraulic oil in the warming-up oil path  144  flows, via the first drain pipe member  215   c , into the first drain port  206   c . The hydraulic oil flowed into the first drain port  206   c  flows into the channel  210   b  (the second channel  210 ) (R 8 ). The hydraulic oil drained from the high-flow switching valve  182  flows, via the first drain pipe member  215   d , into the first drain port  206   d . The hydraulic oil flowed into the first drain port  206   d  flows into the channel  210   b  (the second channel  210 ) (R 9 ). The hydraulic oil passed through the warming-up oil path  144  and the hydraulic oil drained from the high-flow switching valve  182  can therefore be drained. 
     In the relay member  200  described above, the plurality of first channels  208  and the third channel  209  are provided on the main body  201  to align with each other. However, the arrangement is not limited to the order described above. Accordingly, examples shown in  FIGS. 6A, 6B, 6C , which are explained below, can be modified like examples shown in  FIGS. 11A, 11B, and 11C , respectively. Examples shown in  FIGS. 7A and 7B , which are explained below, can be modified like examples shown in  FIGS. 12A and 12B , respectively. In the embodiment, the relay member  200  is a member relaying the pipe members in the work-relating hydraulic system  40 B. However, the identical or similar configuration may be applied to a member relaying pipe members in the travel-relating hydraulic system  40 A. In the embodiment, the relay member  200  relays the third pipe member  213  and the fourth pipe member  214 . However, such a configuration may be applied that does not relay the third pipe member  213  and the fourth pipe member  214 . Furthermore, the present invention is not limited to the configuration described above, as long as, as described in the embodiment, the plurality of first channels  208  and the third channel  209  are provided to align with each other in a single column, and the second channel  210  is provided across the plurality of first channels  208  and the third channel  209 . 
     Specifically, as illustrated in  FIGS. 6A, 6B, and 6C , the plurality of first channels  208  and the third channel  209  may be arranged to align with each other in a plurality of columns, and the second channel  210  may be provided across the plurality of columns to extend in an arrangement direction of the plurality of first channels  208  and the third channel  209 .  FIG. 6A  is a left-front perspective view illustrating the relay member  200  according to a modification example.  FIG. 6B  is a front view illustrating the relay member  200  according to the modification example.  FIG. 6C  is a left-side cross-sectional view illustrating the relay member  200  according to the modification example. In  FIGS. 6A, 6B, and 6C , the arrow A 1  indicates the forward direction, the arrow A 2  indicates the backward direction, the arrow B 1  indicates the leftward direction, and the arrow B 2  indicates the rightward direction. Herein will describe, with mainly reference to  FIGS. 6A, 6B, and 6C , a position relationship among the first channels  208 , the third channel  209 , and the second channel  210  according to the modification example described above. 
     As illustrated in  FIGS. 6B and 6C , the plurality of first channels  208  and the third channel  209  are arranged to align with each other in a plurality of columns. Specifically, the first channel  208   a  and the first channel  208   b  are formed to align in the upper-lower direction on a back part inside the main body  201 . More specifically, the first channel  208   a  and the first channel  208   b  are formed away from the upper part of the main body  201  in an order of the first channel  208   a  and the first channel  208   b . On the other hand, as illustrated in  FIG. 6C , the first channel  208   c , the first channel  208   d , and the third channel  209  are formed to align in the upper-lower direction on a front part inside the main body  201 . More specifically, the first channel  208   c , the first channel  208   d , and the third channel  209  are formed away from the upper part of the main body  201  in an order of the first channel  208   c , the first channel  208   d , and the third channel  209 . 
     As illustrated in  FIG. 6C , the second channel  210  is provided to extend across the plurality of columns. Specifically, the second channel  210  is provided to extend across a column formed by the first channel  208   a  and the first channel  208   b  on a front side inside the main body  201  and a column formed by the first channel  208   c , the first channel  208   d , and the third channel  209  on a back side inside the main body  201 . The second channel  210  is provided to extend from the upper part to the lower part inside the main body  201 . That is, the second channel  210  is provided to extend in the arrangement direction of the plurality of first channels  208  and the third channel  209 . 
     Next, how heat of the hydraulic oil is exchanged in the relay member  200  will be described with mainly reference to  FIG. 6C . As illustrated in  FIG. 6C , the hydraulic oil flowing in the second channel  210  flows from the upper part to the lower part of the main body  201  (R 11 ) to exchange heat with the hydraulic oil flowing in the plurality of first channels  208  and the hydraulic oil flowing in the third channel  209 . Specifically, the hydraulic oil flowing in the second channel  210  first exchanges heat with the hydraulic oil flowing in the first channel  208   a . Next, the hydraulic oil flowing in the second channel  210  exchanges heat with both the hydraulic oil flowing in the first channel  208   b  and the hydraulic oil flowing in the first channel  208   c . The hydraulic oil flowing in the second channel  210  further exchanges heat with both the hydraulic oil flowing in the first channel  208   d  and the hydraulic oil flowing in the third channel  209 . In other words, the hydraulic oil flowing in the second channel  210  simultaneously exchanges heat with both the hydraulic oil flowing in the channels lying in front of the second channel  210  and the hydraulic oil flowing in the channels lying behind the second channel  210 . The hydraulic oil flowing in the second channel  210  can therefore simultaneously exchange heat with both the hydraulic oil flowing in one column of the first channels  208  and the third channel  209  and the hydraulic oil flowing in another one column of the first channels  208 . Efficiency in exchanging heat can therefore be further increased. Compared with a case where the first channels  208  and the third channel  209  are arranged in a single column, the relay member  200  can be formed smaller in the arrangement direction of the plurality of first channels  208  and the third channel  209 . Even when the relay member  200  is to be attached to a relatively narrower region, the relay member  200  can therefore be easily attached to the work machine  1 . 
     In the embodiment described above, the plurality of first channels  208  and the third channel  209  are provided to extend in the width direction inside the main body  201  and are thus orthogonal to the second channel  210 . However, the plurality of first channels  208  and the third channel  209  may be inclined relative to the extending direction (upper-lower direction) of the second channel  210 . In other words, the second channel  210  may be provided to extend and incline relative to the extending direction of the plurality of first channels  208  and the third channel  209 . A case where the second channel  210  is inclined relative to the extending direction of the plurality of first channels  208  and the third channel  209  will be described herein with mainly reference to  FIGS. 7A and 7B .  FIG. 7A  is a left-front perspective view illustrating the relay member  200  according to a modification example.  FIG. 7B  is a front view illustrating the relay member  200  according to the modification example. In  FIGS. 7A and 7B , the arrow A 1  indicates the forward direction, the arrow A 2  indicates the backward direction, the arrow B 1  indicates the leftward direction, and the arrow B 2  indicates the rightward direction. 
     As illustrated in  FIG. 7B , the plurality of first channels  208  and the third channel  209  are inclined downward from one side (left side) to another side (right side). Specifically, the first channel  208   a  and the first channel  208   b  are formed to align in the upper-lower direction on the back part inside the main body  201 , and to incline downward from the left side to the right side. More specifically, the first channel  208   a  and the first channel  208   b  are formed away from the upper part of the main body  201  in an order of the first channel  208   a  and the first channel  208   b . On the other hand, as illustrated in  FIG. 7B , the first channel  208   c , the first channel  208   d , and the third channel  209  are formed to align in the upper-lower direction on the front part inside the main body  201 , and to incline downward from the left side to the right side. More specifically, the first channel  208   c , the first channel  208   d , and the third channel  209  are formed away from the upper part of the main body  201  in an order of the first channel  208   c , the first channel  208   d , and the third channel  209 . 
     Next, how heat of the hydraulic oil is exchanged in the relay member  200  will be described with mainly reference to  FIG. 7B . As illustrated in  FIG. 7B , the hydraulic oil flowing in the second channel  210  flows from the upper part to the lower part of the main body  201  (R 12 ) to exchange heat with the hydraulic oil flowing in the plurality of first channels  208  and the hydraulic oil flowing in the third channel  209 . Specifically, the hydraulic oil flowing in the second channel  210  first exchanges heat with the hydraulic oil flowing in the first channel  208   a . Next, the hydraulic oil flowing in the second channel  210  exchanges heat with both the hydraulic oil flowing in the first channel  208   b  and the hydraulic oil flowing in the first channel  208   c . The hydraulic oil flowing in the second channel  210  further exchanges heat with both the hydraulic oil flowing in the first channel  208   d  and the hydraulic oil flowing in the third channel  209 . In other words, the hydraulic oil flowing in the second channel  210  simultaneously exchanges heat with both the hydraulic oil flowing in the channels lying in front of the second channel  210  and the hydraulic oil flowing in the channels lying behind the second channel  210 . Compared with a case where the first channels  208  and the third channel  209  are orthogonal to the second channel  210 , a region where the first channels  208  and the third channel  209  overlap with the second channel  210  can therefore be fully secured. Efficiency in exchanging heat between the hydraulic oil flowing in the first channels  208  and the third channel  209  and the hydraulic oil flowing in the second channel  210  can therefore be further increased. 
     The arrangement of the plurality of first channels  208  and the third channel  209  is not limited to the configuration described above. As illustrated in  FIG. 8A , the plurality of first channels  208  and the third channel  209  may be arranged around the second channel  210 . A case where the second channel  210  is inclined relative to the extending direction of the plurality of first channels  208  and the third channel  209  will be described herein with mainly reference to  FIGS. 8A and 8B .  FIG. 8A  is a front view illustrating the relay member  200  according to a modification example.  FIG. 8B  is a left-side cross-sectional view illustrating the relay member  200  according to the modification example. In  FIGS. 8A and 8B , the arrow A 1  indicates the forward direction, the arrow A 2  indicates the backward direction, the arrow B 1  indicates the leftward direction, and the arrow B 2  indicates the rightward direction. 
     As illustrated in  FIG. 8B , the plurality of first channels  208 , the third channel  209 , and the second channel  210  extend from one side (left side) to another side (right side). Specifically, the second channel  210  is provided to extend from a center on the right side of the main body  201  to a center on the left side of the main body  201 . The plurality of first channels  208  and the third channel  209  are arranged around the second channel  210  and provided to extend from the center on the right side of the main body  201  to the center on the left side of the main body  201 . Specifically, the first channel  208   a  is arranged in front of and above the second channel  210  and provided to extend from the center on the right side of the main body  201  to the center on the left side of the main body  201 . The first channel  208   b  is arranged in front of and below the second channel  210  and provided to extend from the center on the right side of the main body  201  to the center on the left side of the main body  201 . The first channel  208   c  is arranged behind and below the second channel  210  and provided to extend from the center on the right side of the main body  201  to the center on the left side of the main body  201 . The first channel  208   d  is arranged behind and above the second channel  210  and provided to extend from the center on the right side of the main body  201  to the center on the left side of the main body  201 . The third channel  209  is arranged above the second channel  210  and provided to extend from the center on the right side of the main body  201  to the center on the left side of the main body  201 . That is, the second channel  210  is arranged inside an inner circumference of a virtual circle O rendered by the plurality of first channels  208  and the third channel  209 . 
     Next, how heat of the hydraulic oil is exchanged in the relay member  200  will be described with mainly reference to  FIG. 8B . As illustrated in  FIG. 8B , the hydraulic oil flowing in the second channel  210  flows from the right side to the left side of the main body  201  (R 13 ) to exchange heat with the hydraulic oil flowing in the plurality of first channels  208  and the hydraulic oil flowing in the third channel  209 . Specifically, the hydraulic oil flowing in the second channel  210  exchanges heat with the hydraulic oil flowing in the first channel  208   a  lying in front of and above the second channel  210  across an area from the right side to the left side of the main body  201 . The hydraulic oil flowing in the second channel  210  exchanges heat with the hydraulic oil flowing in the first channel  208   b  lying in front of and below the second channel  210  across an area from the right side to the left side of the main body  201 . The hydraulic oil flowing in the second channel  210  exchanges heat with the hydraulic oil flowing in the first channel  208   c  lying behind and below the second channel  210  across an area from the right side to the left side of the main body  201 . The hydraulic oil flowing in the second channel  210  exchanges heat with the hydraulic oil flowing in the first channel  208   d  lying behind and above the second channel  210  across an area from the right side to the left side of the main body  201 . The hydraulic oil flowing in the second channel  210  exchanges heat with the hydraulic oil flowing in the third channel  209  lying above the second channel  210  across an area from the right side to the left side of the main body  201 . In other words, the hydraulic oil flowing in the second channel  210  simultaneously exchanges heat with both the hydraulic oil flowing in the plurality of first channels  208  and the hydraulic oil flowing in the third channel  209  across an area from the one side (left side) to the other side (right side) of the second channel  210  in the relay member  200 . Such a region that the first channels  208  and the third channel  209  overlap with the second channel  210 , and that the hydraulic oil flowing in the first channels  208  and the third channel  209  warms up the hydraulic oil flowing in the second channel  210  from around the second channel  210  can therefore be fully secured. Efficiency in exchanging heat among the first channels  208 , the third channel  209 , and the second channel  210  can therefore be further increased. 
     The circuits of the hydraulic systems of the work machine  1  are not limited to have the configurations described above, but may be coupled with a warming-up oil path  220 , as illustrated in  FIGS. 9A and 9B .  FIG. 9A  is an enlarged view of a hydraulic system around the brake switching valve  151  according to a modification example.  FIG. 9B  is an enlarged view of a hydraulic system around the relay member  200  according to the modification example. As illustrated in  FIG. 9B , the warming-up oil path  220  is an oil path coupling the oil path  143  and the oil path  145 , as well as is an oil path configured to bypass, for warming-up purpose, the pilot oil heading from the oil path  143 , via the oil path  145 , the warming-up oil path  144 , and the hydraulic oil tank  84 , for example, toward the pilot valves  185 A,  185 B,  185 C, and  185 D. The warming-up oil path  220  is provided with a check valve  221 . As illustrated in  FIG. 9A , the check valve  221  allows the pilot oil to flow from the oil path  143  to the oil path  145 , but disallows the pilot oil to flow from the oil path  145  to the oil path  143 . That is, when the brake switching valve  151  is at the first position  151   a , the pilot oil flowing from the oil path  143 , via the warming-up oil path  220 , to the oil path  145  passes through the brake switching valve  151  and the warming-up oil path  144 , and drains to the hydraulic oil tank  84 . As illustrated in  FIG. 9C , the warming-up oil path  220  is bifurcated from a middle part of the third channel  209  of the relay member  200  to couple the oil path  143  and the oil path  145 .  FIG. 9C  is a front view illustrating the relay member  200  according to the modification example. In  FIG. 9C , the arrow B 1  indicates the leftward direction, and the arrow B 2  indicates the rightward direction. As illustrated in  FIGS. 9B and 9C , a part of the warming-up oil path  220  includes a fifth pipe member  222 , a warming-up port  223 , and a fourth channel  224  (a branch pipe  224 ). The fifth pipe member  222  is a pipe member such as a hose or a pipe and configured to couple the check valve  221  and the relay member  200 . Specifically, for example, an end of the fifth pipe member  222  is coupled to the check valve  221 , whereas another end of the fifth pipe member  222  is coupled to the warming-up port  223 . The fifth pipe member  222  is configured to allow the pilot oil to flow from the warming-up port  223  formed on the relay member  200  to the check valve  221 . As illustrated in  FIG. 9C , the warming-up port  223  is provided on the lower part of the relay member  200 , for example. The fourth channel  224  allows the warming-up port  223  and the third channel  209  to communicate with each other. Specifically, for example, the fourth channel  224  is bifurcated from a middle part of the third channel  209 . The fourth channel  224  is an oil path formed to extend in the upper-lower direction inside the main body  201 . 
     Herein will describe, with mainly reference to  FIG. 9C , a position relationship among the plurality of inlet ports  202 , the plurality of outlet ports  203 , the first supply port  204 , the second supply port  205 , the plurality of first drain ports  206 , the second drain port  207 , the warming-up port  223 , the first channels  208 , the third channel  209 , the second channel  210 , and the fourth channel  224 . As illustrated in  FIG. 9C , different from the configuration described above, the second supply port  205 , the plurality of inlet ports  202 , the second drain port  207 , and the first drain port  206   a  are formed on the side (right side) of the main body  201  to align in the upper-lower direction. Specifically, the second supply port  205 , the plurality of inlet ports  202 , the second drain port  207 , and the first drain port  206   a  are arranged from the upper part on the right side of the main body  201  at predetermined intervals in an order of the second supply port  205 , the inlet port  202   a , the inlet port  202   b , the inlet port  202   c , the inlet port  202   d , the second drain port  207 , and the first drain port  206   a.    
     On the other hand, the first supply port  204 , the plurality of outlet ports  203 , the first drain port  206   b , the first drain port  206   c , and the first drain port  206   d  are formed to align in the upper-lower direction on the other side (left side) of the main body  201 . Specifically, the first supply port  204 , the plurality of outlet ports  203 , the first drain port  206   b , the first drain port  206   c , and the first drain port  206   d  are arranged from the upper part on the left side of the main body  201  at predetermined intervals in an order of the first supply port  204 , the outlet port  203   a , the outlet port  203   b , the outlet port  203   c , the outlet port  203   d , the first drain port  206   b , the first drain port  206   c , and the first drain port  206   d.    
     That is, as illustrated in  FIG. 9C , the third channel  209 , the plurality of first channels  208 , and the second channel  210  are formed to align in the upper-lower direction inside the main body  201 . Specifically, the third channel  209 , the plurality of first channels  208 , and the second channel  210  are arranged from the upper part inside the main body  201  at predetermined intervals in an order of the third channel  209 , the first channel  208   a , the first channel  208   b , the first channel  208   c , the first channel  208   d , and the second channel  210 . 
     As illustrated in  FIGS. 9C and 9D , the fourth channel  224  is provided across the plurality of columns (the plurality of first channels  208  and the second channel  210 ).  FIG. 9D  is a left-side cross-sectional view illustrating the relay member  200  according to the modification example. In  FIG. 9C , the arrow A 1  indicates the forward direction, and the arrow A 2  indicates the backward direction. Specifically, the fourth channel  224  is provided on the back part of the main body  201  to extend in an arrangement direction of the third channel  209 , the plurality of first channels  208 , and the second channel  210 . The fourth channel  224  is formed behind the third channel  209 , the plurality of first channels  208 , and the second channel  210 . 
     Next, how heat of the hydraulic oil is exchanged in the relay member  200  will be described with mainly reference to  FIG. 9C . As illustrated in  FIG. 9C , the hydraulic oil flowing in the fourth channel  224  flows from the upper part to the lower part of the main body  201  (R 14 ) to exchange heat with the hydraulic oil flowing in the plurality of first channels  208  and the hydraulic oil flowing in the second channel  210 . Specifically, the hydraulic oil flowing in the fourth channel  224  first exchanges heat with the hydraulic oil flowing in the first channel  208   a . Next, the hydraulic oil flowing in the fourth channel  224  exchanges heat with both the hydraulic oil flowing in the first channel  208   b  and the hydraulic oil flowing in the first channel  208   c . The hydraulic oil flowing in the fourth channel  224  further exchanges heat with both the hydraulic oil flowing in the first channel  208   d  and the hydraulic oil flowing in the second channel  210 . The hydraulic oil supplied from the hydraulic pump P 1  can therefore exchange heat across the third channel  209 , the first channels  208 , and the second channel  210  due to its relatively higher temperature than a temperature of the hydraulic oil flowing in the oil path configured to allow the hydraulic oil to flow from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180 . The hydraulic oil supplied from the hydraulic pump P 1  can therefore warm up the hydraulic oil flowing from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180  and the hydraulic oil in the oil path configured to drain the hydraulic oil. 
     The work machine  1  described above includes the hydraulic actuators  62  and  63  each configured to be driven by the hydraulic oil, the plurality of control valves  180  configured to control the hydraulic actuators  62  and  63 , the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D configured to adjust the hydraulic oil serving as the pilot oil, the plurality of first pipe members  211  respectively coupled to the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D and configured to allow the pilot oil output from the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D to flow, the plurality of second pipe members  212  respectively coupled to the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the plurality of control valves  180 , the first drain pipe member  215  configured to drain the hydraulic oil, the second drain pipe member  216  configured to return the hydraulic oil to the drain part configured to drain the hydraulic oil, and the relay member  200  including the plurality of inlet ports  202  coupled with the plurality of first pipe members  211 , the plurality of outlet ports  203  coupled with the plurality of second pipe members  212 , the plurality of first channels  208  configured to allow the plurality of inlet ports  202  and the plurality of outlet ports  203  to respectively communicate with each other, the first drain port  206  coupled with the first drain pipe member  215 , the second drain port  207  coupled with the second drain pipe member  216 , and the second channel  210  configured to allow the first drain port  206  and the second drain port  207  to communicate with each other and provided across the plurality of first channels  208 . 
     With the configuration described above, after the work machine  1  is started, the hydraulic oil flows at a relatively lesser amount into the oil path configured to drain the hydraulic oil than an amount of the hydraulic oil flowing in the oil path configured to allow the hydraulic oil to flow from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180 . Even though a further time is required to warm up the oil paths, as long as the hydraulic oil flows into the second channel  210  at pressure lower than pressure of the hydraulic oil flowing in the first channels  208 , the hydraulic oil flowing in the first channels  208  and the hydraulic oil flowing in the second channel  210  can exchange heat. The hydraulic oil flowing from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180  can therefore warm up the hydraulic oil in the oil path configured to drain the hydraulic oil. 
     The plurality of first channels  208  are arranged to align with each other. The second channel  210  is provided to extend in the arrangement direction of the plurality of first channels  208 . 
     With the configuration described above, the plurality of first channels  208  are arranged to align with each other in a single column. The relay member  200  can thus be formed thinner in a direction in which the first channels  208  are orthogonal to the second channel  210 . Even when the relay member  200  is to be attached to a relatively narrower region, the relay member  200  can therefore be easily attached to the work machine  1 . 
     The plurality of first channels  208  are arranged to align with each other in a plurality of columns. The second channel  210  is provided across the plurality of columns to extend in the arrangement direction of the plurality of first channels  208 . 
     With the configuration described above, the hydraulic oil flowing in the second channel  210  can simultaneously exchange heat with both the hydraulic oil flowing in one column of the first channels  208  and the hydraulic oil flowing in another one column of the first channels  208 . Efficiency in exchanging heat can therefore be further increased. Compared with a case where the first channels  208  are arranged in a single column, the relay member  200  can be formed smaller in the arrangement direction of the plurality of first channels  208 . Even when the relay member  200  is to be attached to a relatively narrower region, the relay member  200  can therefore be easily attached to the work machine  1 . 
     The second channel  210  is provided to extend in a direction orthogonal to the extending direction of the plurality of first channels  208 . 
     With the configuration described above, the first pipe member  211 , the second pipe member  212 , the third pipe member  213 , and the fourth pipe member  214  can be attached in different directions. The first pipe member  211 , the second pipe member  212 , the third pipe member  213 , and the fourth pipe member  214  can therefore be easily arranged. 
     The second channel  210  is provided to extend and incline relative to the extending direction of the plurality of first channels  208 . 
     With the configuration described above, compared with a case where the first channels  208  are orthogonal to the second channel  210 , a region where the first channels  208  overlap with the second channel  210  can be fully secured. Efficiency in exchanging heat between the hydraulic oil flowing in the first channels  208  and the hydraulic oil flowing in the second channel  210  can therefore be further increased. 
     The plurality of first channels  208  are arranged around the second channel  210 . 
     With the configuration described above, such a region that the first channels  208  overlap with the second channel  210 , and that the hydraulic oil flowing in the first channels  208  warms up the hydraulic oil flowing in the second channel  210  from around the second channel  210  can be fully secured. Efficiency in exchanging heat between the first channels  208  and the second channel  210  can therefore be further increased. 
     The work machine  1  includes the hydraulic pump P 1  configured to supply the hydraulic oil, the third pipe member  213  configured to allow the hydraulic oil supplied from the hydraulic pump P 1  to flow, and the fourth pipe member  214  coupled to the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D separately from the plurality of first pipe members  211 . The relay member  200  includes the third channel  209  allowing the third pipe member  213  and the fourth pipe member  214  to communicate with each other. 
     With the configuration described above, the hydraulic oil supplied from the hydraulic pump P 1  is relatively higher in temperature than the hydraulic oil flowing in the oil path configured to allow the hydraulic oil to flow from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180 . Efficiency in exchanging heat among the first channels  208 , the third channel  209 , and the second channel  210  can therefore be further increased. 
     The plurality of first channels  208  and the third channel  209  are arranged to align with each other. The second channel  210  is provided to extend in the arrangement direction of the plurality of first channels  208  and the third channel  209 . 
     With the configuration described above, the plurality of first channels  208  are arranged to align with each other in a single column. The relay member  200  can thus be formed thinner in a direction in which the first channels  208  and the third channel  209  are orthogonal to the second channel  210 . Even when the relay member  200  is to be attached to a relatively narrower region, the relay member  200  can therefore be easily attached to the work machine  1 . 
     The plurality of first channels  208  and the third channel  209  are arranged to align with each other in a plurality of columns. The second channel  210  is provided across the plurality of columns to extend in the arrangement direction of the plurality of first channels  208  and the third channel  209 . 
     With the configuration described above, the hydraulic oil flowing in the second channel  210  can simultaneously exchange heat with both the hydraulic oil flowing in one column of the first channels  208  and the third channel  209  and the hydraulic oil flowing in another one column of the first channels  208 . Efficiency in exchanging heat can therefore be further increased. Compared with a case where the first channels  208  and the third channel  209  are arranged in a single column, the relay member  200  can be formed smaller in the arrangement direction of the plurality of first channels  208  and the third channel  209 . Even when the relay member  200  is to be attached to a relatively narrower region, the relay member  200  can therefore be easily attached to the work machine  1 . 
     The second channel  210  is provided to extend in a direction orthogonal to the extending direction of the plurality of first channels  208  and the third channel  209 . 
     With the configuration described above, the plurality of first pipe members  211  and the plurality of second pipe members  212  being in communication with the plurality of first channels  208 , the third pipe member  213  and the fourth pipe member  214  being in communication with the third channel  209 , and the first drain pipe member  215  and the second drain pipe member  216  being in communication with the second channel  210  can be respectively attached in different directions. The plurality of first pipe members  211 , the plurality of second pipe members  212 , the third pipe member  213 , the fourth pipe member  214 , the first drain pipe member  215 , and the second drain pipe member  216  can therefore be easily arranged. 
     The second channel  210  is provided to extend and incline relative to the extending direction of the plurality of first channels  208  and the third channel  209 . 
     With the configuration described above, compared with a case where the first channels  208  and the third channel  209  are orthogonal to the second channel  210 , a region where the first channels  208  and the third channel  209  overlap with the second channel  210  can be fully secured. Efficiency in exchanging heat between the hydraulic oil flowing in the first channels  208  and the third channel  209  and the hydraulic oil flowing in the second channel  210  can therefore be further increased. 
     The plurality of first channels  208  and the third channel  209  are arranged around the second channel  210 . 
     With the configuration described above, such a region that the first channels  208  and the third channel  209  overlap with the second channel  210 , and that the hydraulic oil flowing in the first channels  208  and the third channel  209  warms up the hydraulic oil flowing in the second channel  210  from around the second channel  210  can be fully secured. Efficiency in exchanging heat among the first channels  208 , the third channel  209 , and the second channel  210  can therefore be further increased. 
     The work machine  1  includes the hydraulic pump P 1  configured to supply the hydraulic oil, the hydraulic actuators  62  and  63  each configured to be driven by the hydraulic oil, the plurality of control valves  180  configured to control the hydraulic actuators  62  and  63 , the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D configured to adjust the hydraulic oil serving as the pilot oil, the plurality of first pipe members  211  respectively coupled to the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D and configured to allow the pilot oil output from the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D to flow, the plurality of second pipe members  212  respectively coupled to the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the plurality of control valves  180 , the first drain pipe member  215  configured to drain the hydraulic oil, the second drain pipe member  216  configured to return the hydraulic oil to the drain part configured to drain the hydraulic oil, the third pipe member  213  configured to allow the hydraulic oil supplied from the hydraulic pump P 1  to flow, the fourth pipe member  214  coupled to the plurality of pilot valves  185 A,  185 B,  185 C, and  185 D separately from the plurality of first pipe members  211 , and the relay member  200  including the plurality of inlet ports  202  coupled with the plurality of first pipe members  211 , the plurality of outlet ports  203  coupled with the plurality of second pipe members  212 , the plurality of first channels  208  configured to allow the plurality of inlet ports  202  and the plurality of outlet ports  203  to respectively communicate with each other, the first drain port  206  coupled with the first drain pipe member  215 , the second drain port  207  coupled with the second drain pipe member  216 , the second channel  210  configured to allow the first drain port  206  and the second drain port  207  to communicate with each other, the third channel  209  configured to allow the third pipe member  213  and the fourth pipe member  214  to communicate with each other, and the fourth channel  224  bifurcated from the third channel  209  and provided across the plurality of first channels  208  and the second channel  210 . 
     With the configuration described above, the hydraulic oil supplied from the hydraulic pump P 1  can exchange heat among the third channel  209 , the first channels  208 , and the second channel  210  due to its relatively higher temperature than a temperature of the hydraulic oil flowing in the oil path configured to allow the hydraulic oil to flow from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180 . The hydraulic oil supplied from the hydraulic pump P 1  can therefore warm up the hydraulic oil flowing from the pilot valves  185 A,  185 B,  185 C, and  185 D into the pressure receivers  180   a ,  180   b ,  180   c , and  180   d  of the control valves  180  and the hydraulic oil in the oil path configured to drain the hydraulic oil. 
     The relay member  200  is made of a metallic material. 
     The metallic material normally has higher heat conductivity. With the configuration described above, the hydraulic oil flowing in the second channel  210  can therefore be efficiently heated. 
     The present invention is described above. The embodiment disclosed herein is thought to be not restriction but an example in all aspects. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include equivalent meanings to the claims and all modifications within the scope. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.