Abstract:
A snow removing vehicle has a vehicle body frame and a snow removing member connected directly to a front part of the vehicle body frame for removing snow from a ground surface. The snow removing member has a generally arc-shaped portion curved concavely rearward from the front part of the vehicle body frame. A single wheel axle is rotatably mounted on the vehicle body frame and is disposed in a widthwise central portion thereof so that the vehicle body frame is pivotally movable about the single wheel axle. At least one wheel is mounted on the single wheel axle. A pair of operational handles are connected directly to a rear part of the vehicle body frame so that upward and downward movement of the right and left operational handles relative to the ground surface pivots the vehicle body frame relative to the single wheel axle. When the operational handles are moved upward during removal of snow by the snow removing member, the vehicle body frame and the snow removing member pivot about the single wheel axle so that the front part of the vehicle body frame is inclined downwardly relative to the ground surface and both the driving wheel and a lower end portion of the snow removing member contact the ground surface or a surface of the snow and a chord of the arc-shaped portion extends generally perpendicular to the surface of the ground.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improvement in a hand-pushed snow removing vehicle of small size. 
     2. Description of the Related Art 
     Conventionally, snow plowing tools and machines have been known from, for example, Japanese Utility Model Post-Exam Publication No. SHO-57-41075 and No. SHO-50-30171. 
     Japanese Utility Model Post-Exam Publication No. SHO-5741075 discloses a hand-pushed snow plowing tool simply designed such that an operator hand-pushes the tool with his hands holding operational handles. 
     In Japanese Utility Model Post-Exam Publication No. SHO-50-30171, there is disclosed a powered snow plowing machine which is self-propelled by a motive power source so as to reduce a burden of the operator. 
     The hand-pushed snow plowing tool includes a frame body, a snow-plowing blade provided at a front part of the frame body, and two wheels provided rightwardly and leftwardly of the frame body. The tool includes right and left operational handles extending obliquely and backwardly from a rear part of the frame body. Each operational handle has a grip at an end portion thereof. 
     The powered snow plowing machine includes a towing cart, a snow-plowing blade provided at a front part of the cart, two wheels provided rightwardly and leftwardly of the cart, and right and left operated handles extending backwardly from a rear part of the cart. The machine has an engine as a motive power source. Such an engine is operated to drive the wheels. 
     The tool is simple in construction and can thus be produced at a low cost. The machine is self-propelled by the operation of the engine to thereby reduce a burden of the operator. 
     However, each of the hand-pushed snow plowing tool and the powered snow plowing machine has two wheels provided rightwardly and leftwardly thereof in spaced relation to each other. As a result, the tool and the machine inevitably require large turning radiuses and can harldy make sharp turns. Consequently, both the tool and the machine provide poor mobility and operability. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an easy-to-operate snow removing vehicle designed to reduce a burden of the operator and being capable of making a sharp turn when operated in a narrow workplace. 
     According to an aspect of the present invention, there is provided a hand-pushed snow removing vehicle comprising: a snow removing member provided at a front part of the vehicle so as to push snow; driving wheels provided in a widthwise central portion of the vehicle; a drive source provided in the vehicle so as to drive the driving wheels; right and left operational handles provided at a rear part of the vehicle in such a manner as to extend backwardly of the vehicle; and right and left grips provided at end parts of the right and left operational handles, respectively. 
     The vehicle of the present invention includes the driving wheels provided in the widthwise central portion thereof. Thus, the vehicle can make a sharp turn and provide improved mobility. Consequently, it becomes possible to facilitate removal of snow in a narrow workplace. Moreover, the driving wheels are driven by the drive source to thereby reduce a burden of operating the vehicle on the operator. 
     Preferably, the snow removing member has a width set not to exceed a distance between the right and left grips. Thus, the vehicle can be easily turned during a snow removing operation. 
     In a preferred form of the invention, the snow removing member is arc-shaped in vertical cross-section and disposed such that a chord of the arc lies substantially perpendicularly to a ground when a lower end portion of the snow removing member is set on the ground. With the thus-arranged snow removing member, removed snow moves along the arc having a small radius of curvature, whereby the removed snow does not reach the top of the snow removing member. Thus, a pushing force required to remove snow can be made small to thereby reduce a burden on the operator and the drive source. The chord is substantially perpendicular to the ground, and thereby the snow removing member can be easily attached to or detached from the front part of the vehicle. 
     In a further preferred form of the invention, the snow removing member includes an obliquely upwardly extending bottom sheet serving as a reinforcing rib, the bottom sheet being formed by bending the lower end portion backwardly. As a result, the snow removing member provides improved rigidity. Consequently, there is no need for providing a separate reinforcing member for serving as a reinforcing rib for the snow removing member. The bottom sheet, formed by bending the lower end portion backwardly, extends obliquely and upwardly. It is therefore unlikely that foreign materials get caught between the bottom sheet and the ground during the removal of snow. 
     Preferably, the hand-pushed snow removing vehicle is a single-wheeled electric vehicle having a single one of the driving wheel and an electric motor as the drive source. With only one drive wheel, it becomes possible to facilitate turning of the snow removing vehicle during a snow removing operation. That is, the vehicle can make a sharp turn and hence provide improved mobility. The electric motor used as the drive source produces a small sound when actuated and emits no exhaust gas. Thus, in an area in which residences are closely built, the removal of snow can be assumed even in early mornings or late at night without causing inconveniences to people living there. 
     Preferably, the vehicle further includes batteries for supplying an electric power to the electric motor. The batteries may be disposed between the snow removing member and an axle supporting the driving wheel. The front part of the vehicle becomes heavier to thereby press the driving wheel against the ground. Thus, the driving wheel is prevented from skidding on the ground, thereby enabling the vehicle to propel. With this arrangement, the operational handles for hand-pushing can be lifted up with a small force to thereby provide the vehicle with improved operability. 
     In a still preferred form of the invention, the right or left grip is a slidable grip which slides in correspondemce with a hand-pushing force produced by a hand. The vehicle further includes a detector, disposed proximately to the slidable grip, for detecting an amount of movement of the slidable grip to thereby control the electric motor. The operator can propel the vehicle by grasping and then pushing the grips with his hands. When the grip slides, the amount of movement of the grip is detected by the detector, whereupon the detector outputs a signal. Thereafter, the motor generates an assisting motive power in correspondence with the signal output from the detector, thereby assisting the operator in operating the vehicle. As explained above, the operator can propel the snow removing vehicle by grasping and then pushing the grips with his hands. Otherwise, the operator can propel the vehicle with the aid of the assisting motive power from the motor. For this reason, a further operation for adjusting the assisting motive power is not required. 
     Preferably, the right or left operational handle includes an operation-assist mechanism mounted thereon. The mechanism is designed such that it forcibly pushes the slidable grip towards the vehicle when an assist operation including grasping with a hand held onto the slidable grip is performed. By thus performing an assist operation with the hand held onto the grip, the grip is forcibly pushed towards the vehicle. The electric motor is actuated in correspondence with an amount of movement of the grip thus pushed, thereby assisting the operator in operating the vehicle. Therefore, since the operator can slide the grip without pushing the grip, he can easily obtain the assisting motive power during the removal of snow. 
     In a still further preferred form of the invention, the vehicle further includes stands at the rear part thereof. The vehicle is operated with the right and left operational handles lifted up such that the stands are lifted upwardly off the ground. The vehicle still further includes a control lever disposed in the proximity of the right or left grip, the control lever being operated with fingers or a thumb to control a voltage supplied to the electric motor. The control lever has improved operability, because the control lever can be operated with the fingers or thumb of the hand grasping the grip. Operation of the control lever causes the motor to be actuated to thereby drive the driving wheel. 
     In a still further preferred form of the invention, the vehicle further includes at an upper portion thereof a container for heaping up snow. By virtue of the container provided at the upper portion of the vehicle, the operator can heap snow on the container and then carry the snow to a desired place so as to dump the snow out of the container. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A certain preferred embodiment of the present invention will hereinafter be described in detail, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a snow shoveling machine comprising an electric single-wheel vehicle according to the present invention; 
     FIG. 2 is a side elevation view of the snow shoveling machine shown in FIG. 1; 
     FIG. 3 is a top plan view of the snow shoveling machine shown in FIG. 1; 
     FIG. 4 is an exploded perspective view of a vehicle body frame, a carrier, and bars for the carrier, all of which form the snow shoveling machine in FIG. 1; 
     FIG. 5 is an exploded perspective view showing in detail the vehicle body frame and a snow removing member forming the snow shoveling machine in FIG. 1; 
     FIG. 6 is a side view showing the snow removing member in cross-section. 
     FIG. 7 is a cross-sectional view taken along line  7 — 7  of FIG. 6; 
     FIG. 8 is a side view showing, in cross-section, an operation mechanism and a slidable grip mounted on a right operational handle; 
     FIG. 9 shows a electric circuit designed such that an electric motor supplies an assisting motive power to the snow shoveling machine shown in FIG. 1; 
     FIGS. 10A,  10 B, and  10 C show how the snow shoveling machine shown in FIG. 1 is used; 
     FIGS. 11A,  11 B, and  11 C show relation between a snow removing member and a driving wheel on the ground as the snow shoveling machine of FIG. 1 is used. 
     FIGS. 12A through 12E show how the snow removing member of the present invention and other possible snow removing members remove snow; 
     FIG. 13 shows, partially in cross-section, a modified snow shoveling machine obtained by modifying the machine of FIG. 1 such that two driving wheels are provided in a widthwise central portion thereof; 
     FIG. 14 shows a first alternative operation mechanism obtained by modifying the operation mechanism of FIG. 8 such that an operation-assist mechanism is provided therein; FIG. 15 shows in detail the operation-assist mechanism shown in FIG. 14; 
     FIGS. 16A and 16B illustrates a second alternative operation mechanism obtained by modifying the operation mechanism of FIG. 8; 
     FIG. 17 is a plan view showing, on an enlarged scale, a control lever mechanism shown in FIG. 16A; 
     FIG. 18A is a side elevation view showing the construction of the control lever mechanism in FIG.  16 A and FIG. 18B is a cross-sectional view showing the inner components of the control lever mechanism in FIG.  16 A. 
     FIG. 19 shows how the snow shoveling machine employing the operation mechanism shown in FIG. 16A is used. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description is merely exemplary in nature and is in no way intended to limit the invention, its application or uses. 
     Referring to FIG. 1, there is shown a snow shoveling machine  10 . The snow shoveling machine  10  includes a vehicle body frame  11 , a wheel  12  mounted at a widthwise central portion of the frame  11 , and an electric motor  13  serving as a drive source for the wheel  12 . That is, the machine  10  comprises an electric single-wheel vehicle having a snow removing member  50  mounted thereto. Batteries  15 R,  15 L serving as power supplies for the motor  13  are provided rightwardly and leftwardly of the frame  11 , respectively. Attached to the frame  11  is a motive power transmission mechanism  14  for transmitting a rotational output from the motor  13  to the wheel  12 . On the frame  11 , there is mounted right and left operational handles  16 R,  16 L which are upwardly inclined and extend backwardly from a rear part of the frame  11 . Provided below the rear part of the frame  11  are right and left stands  17 R,  17 L to be placed on the ground. At an upper part of the frame  11 , there is provided a carrier  18 . A container  19  for heaping up snow is detachably mounted at the upper part of the frame  11  or on the carrier  18 , as shown by a phantom line. The snow removing member  50  is removably attached to a front part of the vehicle body frame  11 . The snow shoveling machine  10  is a hand-pushed snow removing vehicle comprising an electric single-wheel vehicle designed such that the motor  13  generates an assisting motive power in correspondence to an operating force produced by an operator so as to assist the operator in operating the machine  10 . 
     The right and left operational handles  16 R,  16 L include right and left grips  21 R,  21 L mounted on end portions thereof. The left operational handle  16 L has a brake lever  22 . The right handle  16 R includes an operation mechanism  70  for controlling whether the motor  13  is actuated. Reference numerals  23 ,  23  denote bars for surrounding the carrier  18 . 
     Turning to FIG. 2, there is shown the vehicle body frame  11  having the front part thereof inclined downwardly such that the snow removing member  50  has a lower end portion  53  close to the ground Gr. The motive power transmission mechanism  14  includes a first reducing mechanism  24 , a transmission shaft  25 , and a second reducing mechanism  26 . The first and second reducing mechanisms  25 ,  26  and the transmission shaft  25  cooperate with each other to transmit a motive power from the electric motor  13  to the wheel  12  through an axle  27 . The first reducing mechanism  24  incorporates a one-way clutch (not shown) for transmitting the motive power only in one direction from the motor  13  to the axle  27 . 
     The right and left batteries  15 R,  15 L are positioned between the axle  27  and the snow removing member  50 . More specifically, as the machine  10  is viewed in side elevation, the batteries  15 R,  15 L are disposed within a space SP defined by the frame  11 . The frame  11  is comprised of a pipe frame. Centers C of the batteries  15 R,  15 L are positioned forwardly of the axle  27 . The motor  13  is disposed in the space SP and is positioned rearwardly and upwardly of the axle  27 . More specifically, centers of gravity of the batteries  15 R,  15 L serving as weights are positioned forwardly of the axle  27  while a center of gravity of an assembly formed by the motor  13  and the first reducing mechanism  24  serving as weights is positioned rearwardly of the axle  27 . Reference numeral  31  designates a controlling device provided within the space SP. 
     With the batteries  15 R,  15 L thus positioned between the axle  27  and the snow removing member  50 , a front portion of the machine  10  is heavier. A pressure required to press the wheel  12  against the ground is thus increased. Therefore, it becomes possible to prevent the wheel  12  from skidding on the ground to thereby ensure that the wheel  12  is driven by the motor  13  to propel the machine  10 . Further, by providing the batteries  15 R,  15 L positioned between the axle  27  and the snow removing member  50 , the weights of the front and rear portions of the machine  10  can be set such that the machine  10  has its improved operability so as to efficiently remove snow. With the weights thus set, a lifting force required for the operator to lift up the operational handles  16 R,  16 L can be made small while an operating force required to operate the handles  16 R,  16 L is also made small. Since the lifting force and the operating force are small, the machine  10  is easy to operate or turn. 
     Reference is made to FIG.  3 . The wheel  12  is disposed in a widthwise center CL of the frame  11  (widthwise center of the machine  10 ). The two batteries  15 R,  15 L are positioned rightwardly and leftwardly of the frame  11 , respectively. The machine  10  has the motor  13  disposed rightwardly of the widthwise center CL as viewed in a direction of movement thereof. 
     The vehicle body frame  11  includes a mounting plate  28  attached to the rear part thereof. In the mounting plate  28 , there are mounted a key switch  28  and a battery residual quantity indicator  34 . 
     A width of the snow removing member  50 , namely, a width L 2  of a snow removing portion  51  is set not to exceed a distance L 1  between the right and left grips  21 R,  21 L. By thus setting the width L 2  and the distance L 1 , it becomes possible to facilitate turning the machine  10  during the removal of snow. When the width L 2  of the snow removing portion  51  is too small, an amount of snow pushed by the snow removing portion  51  is also small. Thus, snow can not be efficiently removed by the machine  10 . When the width L 2  of the snow removing portion  51  is too large, the amount of snow pushed by the snow removing portion  51  is also large. However, the machine  10  can not be easily turned. Therefore, it is preferable that the width L 2  of the snow removing portion  51  is set to be substantially equal to or slightly smaller than the distance L 1  between the right and left grips  21 R,  21 L. 
     FIG. 4 is an exploded perspective view of the vehicle body frame, the carrier, and the bars for the carrier which form the snow shoveling machine. 
     As shown in FIG. 4, the vehicle body frame  11  includes an upper frame  41  formed to have a rectangular configuration as viewed in top plan, and right and left horizontal frames  45 ,  45  both formed to have substantially U-shaped configurations as viewed in side elevation. The frames  45 ,  45  are comprised of round pipes. The frame  11  is comprised of a pipe frame. 
     The upper frame  41  comprises right and left side members  42 ,  42  extending longitudinally of the machine  10 , a front cross member  43  laid between front ends of the side members  42 ,  42 , and a rear cross members  44  laid between rear ends of the side members  42 ,  42 . The members  42 ,  42  are comprised of round pipes. Both of the cross members  43 ,  44  are comprised of squarish pipes. 
     As the left horizontal frame  45  is viewed in side elevation, the frame  45  includes a front vertical portion  46  provided at a front end thereof, a horizontal portion  47  extending horizontally backwardly from a lower end portion of the front vertical portion  46 , and the stand  17 L provided below a rear end portion of the horizontal portion  47  and bent to have a substantially V-shaped configuration. The stand  17 L includes a rear erecting portion  48 . The right horizontal frame  45  has the same construction as the left horizontal frame  45 . 
     The carrier  18  covers the upper frame  41 . The carrier  18  is attached to the cross members  43 ,  44  through mounting brackets  23   a ,  23   a  of the bars  23 ,  23  by means of bolts  67 . 
     Reference is made to FIGS. 5 to  7  showing relation between the vehicle body frame  11  and the snow removing member  50 . 
     As shown in FIG. 6, the front part of the vehicle body frame  11  is inclined downwardly in such a manner as to have the lower end portion  53  of the snow removing member  50  close to the ground Gr. 
     With reference to FIGS. 5 and 6, the member  50  includes the snow removing portion  51  for pushing snow, and guide sheets  52 ,  52  provided rightwardly and leftwardly of the snow removing portion  51  so as to guide snow to the snow removing portion  51 . 
     The snow removing portion  51  of the member  50  has an arc-shaped vertical cross-section curved concavely backwardly thereof. When the snow removing portion  51  has the lower end portion  53  close to the ground Gr as shown in FIG. 6, a chord CH extending through the lower end portion  53  and an upper end  55  of the snow removing portion  51  is substantially perpendicular to the ground Gr. As used herein, the term “the lower end portion  53  close to the ground Gr” means that the lower end portion  53  is close to the ground Gr with a small gap δ provided therebetween, or the lower end portion  53  is in abutment on the ground Gr. 
     More specifically, the snow removing portion  51  is formed by bending a sheet article in such a manner as to have an arc-shaped cross-section of given radius of curvature r. A horizontal sheet  56  extends backwardly from the upper end  55  of the snow removing portion  51 . The horizontal sheet  56  includes a vertical sheet  57  extends upwardly from a rear end thereof. A sheet  58  to be carried on the carrier  18  extends backwardly from an upper end of the vertical sheet  57 . 
     With both the sheet  58  and the vertical sheet  57  on the carrier  18 , the vertical sheet  57  is fasten to the cross member  43  by means of the mounting brackets  23   a  of the bar  23 , the bolt  67 , and a nut  68  so as to attach the snow removing member  50  to the frame  11 . The horizontal sheet  56 , the vertical sheet  57 , and the sheet  58  cooperate with each other to form a mounting portion  59  provided for attaching the snow removing member  50  to the frame  11 . 
     The snow removing portion  51  has an obliquely upwardly extending bottom sheet  54 . The bottom sheet  54  is formed by bending the lower end portion  53  of the snow removing portion  51  backwardly. The bottom sheet  54  serves as a reinforcing rib. The bottom sheet  54  extends along the width of the snow removing portion  51 . By bending a sheet article, there is formed the aforementioned snow removing portion  51  including the bottom sheet  54 , the horizontal sheet  56 , the vertical sheet  57 , and the sheet  58 , all of which are integral with each other. Such a snow removing member  50 , more specifically, the snow removing portion  51  has an increased rigidity because the bottom sheet  54  serves as the reinforcing rib. Since the bottom sheet  54  extends backwardly and is inclined upwardly, it becomes possible to prevent foreign materials from being caught between the bottom sheet  54  and the ground Gr during the removal of snow. 
     Referring to FIG. 7, the snow removing portion  51  includes right and left side ribs  61 ,  61  joined to back surfaces of the right and left end portions of thereof, and right and left intermediate ribs  62 ,  62  joined to back surfaces of an intermediate portion thereof. These ribs  61 ,  61 ,  62 ,  62  are sheet articles extending longitudinally of the machine  10 . 
     The right and left guide sheets  52 ,  52  are respectively secured to outside surfaces of the right and left side ribs  61 ,  61  through bolts  69 ,  69 . The right and left guide sheets  52 ,  52  extend forwardly and outwardly so as to easily collect snow on the snow removing portion  51 . 
     The right and left intermediate ribs  62 ,  62  have right and left stays  64 ,  64  joined to rear ends thereof. The stays  64 ,  64  include recessed portions  63 ,  63 . The front vertical portions  46 ,  46  of the frame  11  are fitted into the recessed portions  63 ,  63 . The stays  64 ,  64  are supported by the front vertical portions  46 ,  46  such that the vehicle body frame  11  can withstand a force acting on the snow removing portion  51  of the snow removing member  50 . 
     Turning back to FIG. 6, a supporting member  65  may be provided to the snow removing member  50  in addition to the stays  64 ,  64 , as shown by a phantom line. In this case, the snow removing member  50  may be bolted to the frame  11  through the supporting member  65 . Designated by reference numeral  66  is a rib. 
     Reference is made to FIG. 8 illustrating constructions of and relation between the operation mechanism  70  and the right grip  21 R provided to the right operational handles  16 R. 
     The right operational handle  16 R is comprised of a pipe material. The handle  16 R includes a round bar  71  attached to an end portion thereof. The grip  21 R has a sliding portion  74  formed from a pipe material, and a grip portion  75  made of rubber. The bar  71  is inserted into the sliding portion  74  such that the sliding portion  74  slides thereon. The grip  21 R covers the sliding portion  74 . Two bushes  72 ,  73  are provided forwardly and backwardly of the sliding portion  74  and fitted into the sliding portion  74 . The bar  71  extends through the bushes  72 ,  73 . 
     The operation mechanism  70  includes a stopper mechanism  76 , a resilient member  77 , an adjustment mechanism  81 , and a detector  92  for detecting the amount of movement of the grip  21 R. 
     The stopper mechanism  76  is provided between the bar  71  and the sliding portion  74 . The stopper mechanism  76  has a pin  78  fixedly mounted to the bar  71 , and a long aperture  74   a  formed in the sliding portion  74  and extending axially of the sliding portion  74 . The pin  78  thus secured to the bar  71  is fitted into the long aperture  74   a  and is perpendicular to an axial line extending longitudinally of the bar  71 . The long aperture  74   a  is designed such that the sliding portion  74  is shifted a predetermined amount of movement S. The long aperture  74   a  and the pin  78  provide the stopper mechanism  76  in combination with each other. With the stopper mechanism  76  thus simply constructed, the amount of movement of the grip  21 R can be regulated. Additionally, the grip  21 R is prevented from rotating on the bar  71 . It is preferable that the pin  78  includes a bumper member  78   a  at a portion thereof abutting on a wall forming the long aperture  74   a , as required. The bumper member  78   a  is made of resilient material such as rubber. 
     The resilient member  77  usually urges the grip  21 R in such a manner as to push the grip  21 R backwardly (rightwardly of this figure). The resilient member  77  comprises a compression spring received in an aperture  71   a  formed in a rear end of the bar  71 . 
     The adjustment mechanism  81  comprises a bolt mounting sheet  82  mounted at a rear end portion of the sliding portion  74 , an adjustment bolt  84  which is screwed into an opening formed in the bolt mounting sheet  82  in such a manner as to press the resilient member  77  by means of a plain washer  83 , and a lock nut  85  for the bolt  84 . The bolt  84  is also screwed into the lock nut  85 . The lock nut  85  is provided for adjusting a repelling force generated by the resilient member  77 . 
     The sliding portion  74  has its front end portion secured to an arm  93  formed from a sheet article. Screwed into the arm  93  is a pushing bolt  94  extending in parallel to the bar  71 . The bolt  94  is locked by the arm  93  through a lock nut  95 . 
     The detector  92  is mounted to the end portion of the operational handle  16 R by means of a bracket  91  provided on the operational handle  16 R. The detector  92  detects the amount of movement of the grip  21 R when the grip  21 R is shifted towards the operational handle  16 R to thereby push a push rod  92   b  provided on the detector  92 . The detector  92  then converts the detected amount of movement into an electric signal. The detector  92  is formed by, for example, a potentiometer  92   a , as shown in FIG.  9 . The push rod  92   b  of the detector  92  extends in parallel to the bar  71 . The push rod  92   b  includes an end portion thereof contacting an end portion of the pushing bolt  94 . The rod  92   b  is pushed by the pushing bolt  94 . The detector  92  is covered with a cover  96  for the detector  92 . The cover  96  is mounted to the operational handle  16 R through screws  97 ,  97 . Reference numeral  79  denotes a packing provided between the bar  71  and the sliding portion  74  to prevent water from flowing into a space therebetween. 
     Discussion will be made next as to operation of the thus arranged operation mechanism  70  with reference to FIG.  8 . 
     By grasping the grip  21 R and then pushing the same towards the handle  16 R (leftwardly of this figure), a pushing force is generated. Such a pushing force is applied to the resilient member  77  through the sliding portion  74 , the bolt mounting sheet  82 , the adjustment bolt  84 , and the plain washer  83 . Then, the grip  21 R is slid towards the handle  16 R against the repelling force produced by the resilient member  77 , whereupon the pushing bolt  94  is slid by the same amount of movement as the grip  21 R to thereby push the push rod  92   b  of the detector  92 . The detector  92  outputs an electric signal corresponding to the amount of movement of the push rod  92   b.    
     When the grip  21 R is freed from the pushing force, the grip  21 R is automatically returned to its original position, as shown in FIG. 8, by the repelling force generated by the resilient member  77 . Thus, the electric signal output from the detector becomes zero. 
     Shown in FIG. 9 is an electric circuit for the snow shoveling machine of the present invention. The circuit as shown in FIG. 9 is designed such that the electric motor  13  is controlled by the operation mechanism  70 . 
     The electric circuit for the machine comprises the controlling device  31 , the batteries  15 R,  15 L, the key switch  32  serving as a main switch and connected between the batteries  15 R,  15 L and the controlling device  31 , the detector  92  of the operation mechanism  70 , the electric motor  13 , a vehicle velocity detecting portion  33  for detecting a rotational speed of the motor  13 , and the battery residual quantity indicator  34  for indicating residual power in the batteries  15 R,  15 L. All the key switch  32 , the detector  92 , the electric motor  13 , the vehicle velocity detecting portion  33 , and the indicator  34  are connected to the controlling device  31 . 
     The controlling device  31  serves such a function of controlling the motor  13  as controlling a voltage supplied to the motor  13  in correspondence to the electric signal output from the detector  92  when the level of the electric signal output from the detector  92  is higher than a predetermined level. 
     Turning to FIGS. 10A to  10 C, snow is removed using the snow shoveling machine of the present invention. 
     As shown in FIG. 10A, the snow shoveling machine  10  is propelled by an operator M so as to remove snow. Removal of snow is effected by pushing snow forwardly with the snow removing member  50 . When the pushing force generated by grasping and then pushing the grips  21 R,  21 L with hands is small, the amount of movement of the grip  21 R is also small. The detector  92  as shown in FIG. 10B thus outputs an electric signal having a low level. The level of such an electric signal is not higher than the predetermined level, and therefore the device  31  as shown in FIG. 9 does not supply to the motor  13  a control signal for controlling the motor  13 . This means that when the pushing force is smaller than a reference pushing force that causes the motor  13  to generate the assisting motive power, the device  31  does not generate the control signal and thus the motor  13  does not generate the assisting motive power, either. In such a case, the snow shoveling machine  10  is traveled by such a small pushing force produced by the operator M alone. As the snow shoveling machine  10  is traveled by the small pushing force, rotation of the wheel  12  is not transmitted to the motor  13  because the first reducing mechanism  24  as shown in FIG. 2 incorporates the one-way clutch (not shown). 
     When the pushing force produced by grasping and then pushing the grips  21 R,  21 L with the hands is larger than the reference pushing force, the amount of movement of the grip  21 R in FIG. 10B is provided which corresponds to the pushing force thus produced. Then, the detector  92  outputs the electric signal in correspondence to such an amount of movement of the grip  21 R. On the basis of the electric signal output from the detector  92  in the manner as stated above, the device  31  as shown in FIG. 9 supplies the control signal to the motor  13 . The electric signal output from the detector  92  varies in correspondence to the pushing force produced by pushing the grip  21 R. The motor  13  is controlled by the device  31  in such a manner as to output the assisting motive power corresponding to the control signal supplied from the device  31 . By thus pushing the grip  21 R with the pushing force larger than the reference pushing force, the motor  13  is operated to produce the assisting motive power for assisting the operator M in operating the machine  10 . 
     Referring to FIG. 10C, snow is heaped up in the container  19 . The operator M carries the snow to the desired place at which the snow is dumped out of the container. It will be appreciated that whether the operator M propels the machine  10  with or without the aid of the assisting motive power from the motor  13  depends upon the magnitude of the pushing force produced by grasping and then pushing the grip  21 R in the manner as described with reference to FIG.  10 A. 
     The operator M pushes the machine  10  with his hands grasping the grips  21 R,  21 L, regardless of whether the operator M propels the machine  10  with or without the aid of the assisting motive power. 
     FIGS. 11A to  11 C illustrate how the snow shoveling machine  10  is operated to remove snow. 
     With reference to FIG. 11A, the machine  10  is propelled to remove snow. Removal of snow is effected by pushing snow forwardly with the snow removing member  50 . During the removal of snow, the lower end portion  53  of the snow removing portion  51  pierces accumulated snow. The wheel  12  positioned in the widthwise central portion of the machine has a lower end portion  12   a  thereof contacting the ground Gr or a surface Sn of unremoved snow. Whether the lower end portion  53  contacts snow throughout the width thereof as shown in FIG. 11B, or has at least two points A, B contacting the snow as shown in FIG. 11C depends upon the extent to which the lower end portion  53  pierces the snow. 
     Therefore, as snow is removed by the snow shoveling machine  10 , at least three supporting points including the lower end portion  12   a  of the wheel  12 , and the points A, B of the snow removing portion  51  contact the ground Gr or the surface Sn, as viewed in plan. By thus providing at least the three supporting points, the machine  10  can be traveled stably. The thus constructed snow shoveling machine  10  can steadily remove snow. 
     FIGS. 12A to  12 E illustrate how the snow removing portion  51  of the present invention, and other possible snow removing portions are operated upon the removal of snow. 
     Shown in FIG. 12A is the snow removing portion  51  of the present invention. The snow removing portion  51  has an arced cross-section. The snow removing portion  51  is disposed such that the chord CH extends substantially perpendicularly to the ground Gr when the lower end portion  53  is placed on the ground Gr. Snow SN is pushed forwardly by the snow removing portion  51  while moving upwardly along the arced cross-section of the snow removing portion  51  and falling. The snow SN moves along an arc having a small radius of curvature, such that the snow SN does not reach the top of the snow removing portion. Therefore, the snow SN can be removed with an optimal pushing force. Since the chord CH extend perpendicularly to the ground Gr, the snow removing portion  51  can be easily mounted to the vehicle frame  11 . 
     Referring to FIG. 12B, there is shown a first snow removing portion  51 B to be compared with the snow removing portion  51 . The snow removing portion  51 B is formed by a sheet article substantially perpendicularly disposed on the ground Gr. The snow removing portion  51 B compresses snow SN placed at the front thereof. As a result, a very large force is undesirably required to push the snow SN. 
     Turning to FIG. 12C, there is shown a second snow removing portion  51 C to be compared with the snow removing portion  51 . The snow removing portion  51 C is formed by a sheet article inclined backwardly at a given angle β 1  (an acute angle) to the ground Gr. The top of the snow removing portion  51 C is covered with snow SN. The snow SN is likely to fall from the top of the snow removing portion  51 C to the ground Gr. Therefore, the snow SN can not be efficiently removed. Further, the snow removing portion  51 C increases in weight because of the snow SN on the top thereof, whereby a large force is undesirably required to push the snow removing portion  51 C. 
     FIG. 12D illustrates a third snow removing portion  51 D to be compared with the snow removing portion  51 . The snow removing portion  51 D has an arc-shaped cross-section. The snow removing portion  51 D is inclined backwardly with a lower end portion d thereof on the ground Gr, such that a given angle β 2  (obtuse angle) is provided between the ground Gr and a chord CH extending between the lower end portion d and an upper end portion of the snow removing portion  51 D. Snow SN is pushed forwardly by the snow removing portion while moving upwardly along the arced cross-section of the snow removing portion  51 D and falling. Since the snow removing portion  51 D is inclined backwardly, the uppermost portion of the snow SN is higher than the upper end portion of the snow removing portion  51 D. The snow SN moves along an arc having a large radius of curvature, and hence a large force is required to push the snow SN. Moreover, because the chord CH is inclined relative to the ground Gr, it is difficult to attach the snow removing portion  51 D to the vehicle body frame. 
     Shown in FIG. 12E is a fourth snow removing portion  51 E to be compared with the snow removing portion  51 . The snow removing portion  51 E has an arc-shaped cross-section. The snow removing portion  51 E is inclined forwardly with a lower end portion e thereof placed on the ground Gr, such that a given angle β 3  (obtuse angle) is provided between the ground Gr and a chord CH extending between the lower end portion e and an upper end portion of the snow removing portion  51 E. The snow removing portion  51 E compresses snow SN placed at the front thereof, whereby a large force is undesirably required to push the snow SN. Further, because the chord CH is inclined relative to the ground Gr, it is difficult to attach the snow removing portion  51 E to the vehicle body frame. 
     Reference is made to FIG. 13 showing an alternative snow shoveling machine obtained by modifying the machine  10  according to the present invention. The container  19  and the snow removing member  50  are omitted for clarity. 
     The modified snow shoveling machine  10  has right and left wheels  12 ,  12  as driving wheels disposed side by side in a widthwise central portion of the frame  11 . More specifically, the right and left wheels  12 ,  12  are disposed on an axle  27  and adjoin to each other. In all other material respects, the snow shoveling machine  10  of FIG. 13 is identical to that as described with reference to FIG. 1 to FIG.  11 . Therefore, parts corresponding to those as discussed with reference to FIG. 1 to FIG. 13 are denoted by like reference numerals, and their description is omitted. 
     Referring to FIGS. 14 and 15, there is shown a first alternative operation mechanism obtained by modifying the operation mechanism  70  as shown in FIG.  8 . 
     The operation mechanism as shown in FIG. 14 is identical to the operation mechanism  70  as shown in FIG. 9 except that the former includes an operation-assist mechanism  100 . More specifically, the handle  16 R has the operation-assist mechanism  100  for pushing the grip  21 R towards the vehicle body frame  11  by subjecting the slidable grip  21 R to an assist operation with a hand holding the grip  21 R. 
     As shown in FIGS. 14 and 15, a loop member  101  includes one end portion  101 A held by the bracket  91  so that the end portion  101 A swings in such a direction as to come into and out of contact with the grip  21 R. The loop portion  101  extends substantially along a longitudinal direction of the bar  71 . More specifically, the loop member  101  extends backwardly of the grip  21 R beyond the arm  93  secured to the sliding portion  74 . The loop member  101  includes another end portion  101 B held by a longitudinally intermediate portion  102   a  of an auxiliary lever  102  which swings in the same direction as the loop member  101 . The lever  102  has a finger catching portion  102   b  at its one end. At another end of the lever  102 , there is formed a push portion  102   c  inclined towards the operational handle  16 R at a predetermined angle θ to the loop member  101 . The push portion  102 C abuts on the arm  93 . A projection supporting portion  75   a  projects from the grip  21 R and contacts a portion between the intermediate portion  102   a  of the lever  102  and the push portion  102   c . The projection supporting portion  75   a  serves as a fulcrum on which the lever  92  turns. The projection supporting portion  75   a  forms the outer peripheral surface of a grip guard portion  75   b  provided at an end portion of the grip portion  75 . 
     The bracket  91  is secured to the end portion of the handle  16 R. The bracket  91  extends perpendicularly to a longitudinally extending center axis of the handle  16 R. Also, the bracket  91  extends in parallel to the arm  93 . Therefore, the bracket  91  and the arm  93  are opposed to each other. 
     The loop member  101  is formed by bending such a resilient wire article as a piano wire and then laying bent end portions  101   a ,  101   a  one over the other. The loop member  101  extends in the same direction as the handle  16 R and substantially takes the form of a rectangle. The end portions  101   a ,  101   a  form the end portion  101 B in cooperation with each other. 
     The intermediate portion  102   a  of the lever  102  has a supported structure comprised of a supported pipe  103  fitted into an aperture formed in the lever  102 , and push nuts  104 ,  104  provided on outer peripheral surfaces of both end portions of the pipe  103 . The pipe  103  is pressed into the nuts  104 ,  104 . The nuts  104 ,  104  are provided for preventing the pipe  103  from coming out. The end portions  101   a ,  101   a  of the loop member  101  are inserted into the pipe  103  through right and left sides of the pipe  103 , respectively. With this arrangement, the intermediate  102   a  is supported such that the lever  102  swings in the manner as discussed above. 
     The bracket  91  takes the form of a trapezoid and includes right and left sloped locking portions  91   a ,  91   a  provided rightwardly and leftwardly thereof. Because the locking portions  91   a ,  91   a  hold the end portion  101 A of the loop member  101 , the loop member  101  is swingably supported by the bracket  91 . Both of the locking portions  91   a ,  91   a  extend outwardly and downwardly to thereby limit the swinging motion of the loop member  101  away from the handle  16 R. In other words, the locking portions  91   a ,  91   a  serves as a stopper mechanism for limiting a separation swing angle a as shown in FIG.  14 . These locking portions are hereinafter referred to as first stoppers  91   a ,  91   a.    
     The loop member  101  is disposed to have the limited separation swing angle a, whereby the push portion  102   c  of the lever  102  abuts on a predetermined position on the arm  93 . Consequently, the position of the arm  93  on which the push portion  102   c  abuts is substantially fixed. Thus, the position of the finger catching portion  102   b  of the lever  102  is also fixed. 
     The loop member  101  includes right and left linear portions  101 D,  101 C both detachably supported by a second stopper  105 . 
     The grip portion  75  has the grip guard portion  75   b  protruding radially from the end portion thereof. A third stopper  75   c  forming a surface of the grip guard portion  75   b  is opposed to the arm  93 . The lever  102  includes a projecting portion  102   d  formed integrally therewith. 
     The second and third stoppers  105 ,  75   c  as well as the first stopper  91   a ,  91   a  are provided for limiting the separation swing angle α. The bracket  91  is attached to the detector  92  through bolts and nuts  98 ,  98 . 
     Discussion will be made as to the operation of the operation-assist mechanism  100  with reference to FIG.  14 . 
     With a hand grasping the grip  21 R and with the fingers of the hand on the finger catching portion  102   b , the lever  102  is pushed upwardly as shown by an arrow U, whereupon the push portion  102   c  pushes a back surface of the arm  93  towards the handle  16 R. A force having the same magnitude as the pushing force that pushes the arm  93  is then applied to the resilient member  77  through the sliding portion  74 , the bolt mounting sheet  82 , the adjustment bolt  84 , and the plain washer  83 . Thus, the grip  21 R is slid by an amount of movement corresponding to the force that pushes up the finger catching portion  102   b.    
     That is, the force that pushes up the lever  102  is converted into a force that slides the grip  21 R towards the handle  16 R. Since the grip  21 R is slid the amount of movement corresponding to the force that pushes up the finger catching portion  102   b , the detector  92  detects such an amount of movement to thereby outputs the electric signal. Then, the controlling device  31  supplies the control signal to the motor  13  on the basis of the electric signal thus output from the detector  92 . The electric signal output from the detector  92  varies in correspondence to the force that pushes up the finger catching portion  102   b . The device  31  controls in such a manner as to cause the motor  13  to produce the corresponding assisting motive power. With this arrangement, the assisting motive power is generated on the basis of the operation of the lever  102  to thereby assist the operator M in operating the machine  10 . 
     When the fingers cease to push up the finger catching portion  102   b , the grip  21 R and the lever  102  are returned to their original positions by the repelling force produced by the resilient member  77 . Consequently, the detector  92  does not output the electric signal. 
     The first alternative operation mechanism  70  thus arranged is advantageous not only in that the grip  21 R is pushed by the force larger than a predetermined force to thereby automatically adjust the assisting motive power, but also in that the auxiliary lever  102  is operated to thereby freely generate the assisting motive power without depending on the force that pushes the grip  21 R. Therefore, the snow shoveling machine can be propelled with the force smaller than the predetermined force that pushes the grip  21 R. 
     Reference is made next to FIGS. 16 to  19  showing a second alternative operation mechanism according to the present invention. 
     FIG.  16 A and FIG. 16B schematically show the construction of the second alternative operation mechanism. 
     As shown in FIGS. 16A and 16B, the operation mechanism for the snow shoveling machine comprises a control lever mechanism  110 . The control lever mechanism  110  includes a control lever  111 . When the lever  111  is turned by a thumb F to pull a throttle wire  114 , a potentiometer  120  is operated. 
     The potentiometer  120  comprises a rheostat including a case  121 , a pin  122 , and a lever  123  mounted to the case  121  through the pin  122 . When the throttle wire  114  is pulled to turn the lever  123 , the pin  122  is rotated to thereby move a sliding contact (not shown) incorporated in the case  121 . The pin  122  is provided with a torsion spring for usually urging the pin  122  in such a manner that the pin  122  is automatically returned to its original state in which the pin  122  is not turned. 
     In the second alternative operation mechanism, since the potentiometer  120  is directly connected to the electric motor  13  as shown in FIG. 9, the motor  13  can be directly controlled with the potentiometer  120 . Thus, a voltage supplied to the motor  13  is controlled by the control lever  111  through the potentiometer  120 . 
     In lieu of the detector  92  as shown in FIG. 9, the potentiometer  120  may be connected to the device  31 . In this case, the device  31  functions to control the motor  13  in correspondence to an output from the potentiometer  120 . For example, the device  31  controls a voltage provided to the motor  13 . 
     Reference is made to FIG. 17 showing in top plan the control lever mechanism  110  of FIG. 16A serving as the operation mechanism. The lever  111  of the control lever mechanism  110  is disposed in the proximity of the right grip  21 R. In other words, the lever is provided on a side of the widthwise central portion of the machine. More specifically, the lever  111  is disposed in such a position as to be operated by the thumb F of a right hand H grasping the grip  21 R. 
     The control lever mechanism  110  is mounted on the handles  16 R by means of a mounting band referenced by numeral  117 . In this embodiment, the right and left grips  21 R,  21 L are stationary grips that do not slide unlike the grips previously described. 
     As best shown in FIG.  18 A and FIG. 18B, the control lever mechanism  110  is constructed such that the lever  111  is turned downwardly with the thumb F of the right hand H on an end portion of the lever  111  to thereby turn a relaying lever  113  on a pin  112  clockwise so as to pull the throttle wire  114  in a direction from the left to the right in this figure. The control lever mechanism  110  includes a torsion spring  115  wound on the pin  112 . The relaying lever  113  is usually urged by the torsion spring  115  in such a manner as to turn counterclockwise. When the thumb F is taken off the control lever  111 , the relaying lever  113  is turned counterclockwise to return the throttle wire  114  to its original state. 
     The pin  112  extends in a direction perpendicular to this sheet in such a manner as to pass through a case  116 . The pin  112  includes a projection portion protruding from the case  116 . The lever  111  is mounted on such a projection portion. 
     Referring back to FIG. 16A, when the thumb F is taken off the lever  111 , the torsion spring  115  acts to return the lever  111  to its original state in which the lever is not operated. The lever  123  of the potentiometer  120  is also returned to its original state in which the lever  123  is not turned. Therefore, the voltage supplied to the electric motor nearly becomes zero to thereby bring the rotational speed of the motor to zero. 
     As shown in FIG. 16B, when the lever  111  is turned clockwise, the throttle wire  114  is pulled towards the control lever mechanism  110  to thereby turn the lever  123  of the potentiometer  120  clockwise. Consequently, the voltage provided to the motor increases to thereby increase the velocity of the snow shoveling machine. 
     FIG. 19 illustrate the snow shoveling machine having the second alternative operation mechanism. As shown in this figure, the operator M propels the snow shoveling machine  10  to push snow forwardly with the snow removing member  50  so as to removal the same. 
     So as to propel the machine  10 , the operator M lifts up the operational handles  16 R,  16 L with his hands grasping the right and left grips  21 R,  21 L, such that the stands  17 R,  17 L (the only left stand  17 L shown) is lifted upwardly off the ground. Then, the operator M pushes the right and left grips  21 R,  21 L to thereby propel the machine  10  without the aid of the motive power supplied from the motor. 
     For propelling the traveling machine  10  with the motive power supplied from the motor  13 , the operator M turns the lever  111  downwardly with his thumb F on the lever  111  and with the right hand H grasping the grip  21 R. The voltage supplied to the motor  13  is then increased by means of the potentiometer  120  to thereby cause the motor  13  to generate the motive power. The machine  10  is self-propelled by such a motive power. The voltage supplied to the motor  13  increases in correspondence to the operation of the control lever  111  to thereby increase the velocity of the snow shoveling machine  10 . 
     As is apparent from the foregoing description, the operator M lifts up the operational handles  16 R,  16 L with his hands grasping the grips  21 R,  21 L, such that the right and left stands  17 R,  17 L are lifted upwardly off the ground. The operator M then hand-pushes the snow shoveling machine  10  without the aid of the motive power from the motor  13 . Alternatively, by operating the lever  111  with the thumb F on the lever  111  and with the hand H grasping the grips  21 R, the motor  13  then generates the motive power, such that the machine  10  is self-propelled with such a motive power. 
     The present invention is not limited to the embodiments as described above. That is, an engine as well as the electric motor may be the drive source for the snow shoveling machine. The operation mechanism  70  or the control lever  11  may be mounted at the left operational handle  21 L. 
     Obviously, various minor changes and modifications of the present invention are possible in the light of the above teaching. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described.