Abstract:
A walking-type snow removal machine comprises a snow removing member provided at a front part of a body frame for pushing snow forward, and crawler belts provided on right and left sides of the body frame. The body frame carries thereon an electric motor and a battery. The electric motor drives right and left drive wheels to drive the crawler belts. The electric motor generates little noise as compared with an engine, and contributes to downsizing of the snow removal machine. The battery supplies electrical power to the electric motor.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an improvement in a walking type snow removal machine which is self-propelled by power.  
           [0003]    2. Description of the Related Art  
           [0004]    In recent years, auger-type snow removal machines which are self-propelled by power and operated by operators walking with the machines have been extensively used to reduce the workload of the operators in clearing snow in a small area. An example of such auger-type snow removal machines is disclosed in, for example, Japanese Patent Laid-Open Publication No. SHO-63-293208 entitled “POWER TRANSMITIION DEVICE FOR SNOW REMOVAL MACHINE”.  
           [0005]    The disclosed snow removal machine comprises an auger and a blower provided at a front part of the body, handles provided at a rear part of the body. The auger, blower and right and left crawlers are driven by engine power provided via a transmission. The snow removal machine is of a walking type and is relatively small.  
           [0006]    However, the snow removal machine is arranged such that snow raked in by the auger is thrown away with the blower through a shoot, thereby limiting a place to clear of snow. For example, there is a limit in using the auger-type snow removal machine in a small area such as a residential area in the suburbs or an urban district. Further, since it employs an engine as a power source, due care should be taken as to noises generated by the engine, especially when the auger-type snow removal machine is used at a quiet time, i.e., in an early morning or at midnight in a residential area or an urban district.  
           [0007]    In this context, there has been a demand for a walking-type snow removal machine which can be used easily at any time even in such a small area as a residential area in the suburbs or an urban district.  
           [0008]    Further, in the snow removal machine disclosed in the above-mentioned publication, the right and left crawlers always have the same running speed. Accordingly, when the running direction of the snow removal machine is changed or corrected, difference in rotational speed between the right and left crawlers cannot be absorbed. It is thus required to hold up the snow removal machine with human power to suspend in midair one of the crawlers to change the direction. However, the snow removal machine runs with the crawlers having larger ground-contacting surfaces and has a larger turning radius, thereby presenting a problem of difficult turning.  
         SUMMARY OF THE INVENTION  
         [0009]    It is therefore an object of the present invention to provide a walking-type snow removal machine that can be used easily at any time and turns easily with agility.  
           [0010]    According to one aspect of the present invention, there is provided a snow removal machine comprising a body frame, a snow removing member provided at the front of the body frame for pushing out snow, operating handles provided at the rear of the body frame, crawler belts provided on the right and left sides of the body frame, an electric motor provided on the body frame for driving the right and left crawler belts through right and left drive wheels, and a battery provided on the body frame for supplying electric power to the electric motor.  
           [0011]    The electric motor supplied with power by the battery drives the right and left crawler belts through the right and left drive wheels. The operator controls the operating handles while walking to propel the snow removing machine. The snow removing member provided at the front of the body frame pushes out snow forward to remove snow easily. Thus the snow removal machine can be used even in a small area. Since the electric motor is used as a drive source, the snow removal machine can be made small as compared with a snow removal machine employing an engine. In addition, it generates very small noise and can be used at any time from early morning till midnight.  
           [0012]    In a preferred form, the snow removal machine further comprises a control device for controlling the electric motor. The right and left drive wheels are desirably disposed at the front part of the right and left crawler belts. The electric motor is desirably disposed in such a manner that the center of gravity of the electric motor is positioned in the vicinity of the center of axles of the right and left drive wheels. The battery is disposed in such a manner that the center of gravity of the battery is positioned behind the center of gravity of the electric motor. The control device is disposed in such a manner that the center of gravity of the control device is positioned behind the center of gravity of the battery. That is, the electric motor and the battery of relatively large weight are positioned in forward positions, whereby the center of gravity of the snow removal machine is positioned forward, so that the snow removing member easily plunges into snow. Further, since the center of gravity of the snow removal machine is biased to the side of the drive wheels, the driving force of the drive wheels on the crawler belts can be sufficiently obtained. More specifically, the center of the motor shaft of the electric motor may be disposed above and ahead of the center of the axles of the drive wheels. Further, it is preferred to dispose the control device in a position to prevent it from snow damage.  
           [0013]    Desirably, an extension line of the body frame is arranged to pass substantially over the center point of a height of the snow removing member on a snow removing surface of the snow removing member when the body frame is inclined with its front part held downward. In removing snow, snow force acting on the snow removing member in an upwardly slanting direction to the rear is supported on the shaft center of the body frame in the longitudinal direction. Thus, large eccentric load does not act on the body frame.  
           [0014]    Preferably, the snow removal machine further comprises a differential gear interposed between the axles on which to couple the right and left drive wheels. Power of the electric motor is transmitted to the right and left drive wheels through the differential gear and the axles. Accordingly, when the running direction of the snow removal machine is changed or corrected, difference in rotational speed between the right and left drive wheels is absorbed by the differential gear. Thus, the snow removal machine can easily change its direction and has a smaller turning radius.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    A preferred embodiment of the present invention will be described in more detail below, by way of example only, with reference to the accompanying drawings, in which:  
         [0016]    [0016]FIG. 1 is a side view showing a snow removal machine according to the present invention;  
         [0017]    [0017]FIG. 2 is a top plan view of the snow removal machine shown in FIG. 1;  
         [0018]    [0018]FIG. 3 is an exploded perspective view of the snow removal machine shown in FIG. 1;  
         [0019]    [0019]FIG. 4 is a schematic top plan view of crawler belts, a drive mechanism and its surroundings of the snow removal machine shown in FIG. 1;  
         [0020]    [0020]FIG. 5 is an enlarged sectional view of the snow removal machine taken along line  5 - 5  of FIG. 2;  
         [0021]    [0021]FIG. 6 is an enlarged perspective view showing details of an expansion mechanism provided at the rear of the snow removal machine of FIG. 1;;  
         [0022]    [0022]FIG. 7 is a partial sectional view of a mounting structure of the lower part of the expansion mechanism and an adjusting lever mechanism;  
         [0023]    [0023]FIG. 8A is al sectional view of the expansion mechanism of FIG. 6 in the most-extended state, while FIG. 8B is an enlarged sectional view of a part denoted by reference character “b” of FIG. 8A;  
         [0024]    [0024]FIG. 9 is a schematic side elevational view showing the positional relationship between the components of the snow removal machine according to the present invention;  
         [0025]    [0025]FIG. 10 is a schematic side elevational view showing an operation of the snow removal machine in a normal state in which its body frame is inclined halfway for snow removal;  
         [0026]    [0026]FIG. 11 is a view similar to FIG. 10 but showing a sectional view of the snow removal machine in a state in which the expansion mechanism is extended the most;  
         [0027]    [0027]FIG. 12A is a top plan view showing an operation of the snow removal machine in linear forward motion;  
         [0028]    [0028]FIG. 12B is a schematic diagram showing a power transmission mechanism of the snow removal machine in such motion;  
         [0029]    [0029]FIG. 13A is a top plan view showing an operation of the snow removal machine making a right turn; and  
         [0030]    [0030]FIG. 13B is a schematic diagram showing the power transmission mechanism of the snow removal machine making such a turn.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]    The following description is merely exemplary in nature and is in no way intended to limit the invention, its application or uses.  
         [0032]    As shown in FIGS. 1 and 2, a snow removal machine  10  has a snow removing member  20  at the front of a body frame  11 . Crawler belts  31 R,  31 L (See FIG. 2) are provided on the right and left sides of the body frame  11 , respectively. Right and left operating handles  41 ,  41  are provided at the rear of the body frame  11 . An electric motor  51 , a power transmission mechanism  60 , a pair of right and left batteries  101 ,  101 , a charger  103  and a control device  105  are mounted to the body frame  11 . The snow removal machine  10  is a walking-type snow removal machine that is self propelled with the electric motor  51  driving as a drive source the pair of right and left crawler belts  31 R,  31 L, while being controlled by the operator not shown in the figures walking with the operating handles  41 ,  41 .  
         [0033]    The pair of batteries  101 ,  101  are electric sources supplying electric power to the electric motor  51 , which batteries are mounted to the upper part of the body frame  11  through a battery box  102 .  
         [0034]    The charger  103  charges the batteries  101 ,  101  with a plug  104  inserted into an AC power receptacle of a home power source or the like. The charger  103  is attached to the battery box  102 .  
         [0035]    The control device  105  controls the electric motor  51  based on signals from a operating panel  106  provided on the operating handles  41 ,  41  and a potentiometer that is described later. The control device  105  is attached to the side of the charger  103 . In FIG. 1, the reference numeral  38  designates a belt biasing member and  107  designates a cover.  
         [0036]    Right and left drive wheels  32 R,  32 L are disposed on the front side of the right and left crawler belts  31 R,  31 L. Right and left rolling wheels  33 R,  33 L are disposed on the rear side of the right and left crawler belts  31 R,  31 L. The crawler belts  31 R,  31 L are wound around the drive wheel  32 R and the rolling wheel  31 R, and  32 L and  31 L, respectively.  
         [0037]    The right and left operating handles  41 ,  41  extend backwardly from the rear of the body frame  11 . The operating handles  41 ,  41  have grips  44 ,  44  at their ends. In the vicinity of the right grip  42 , a operating lever  44  for changing the rotational number of the electric motor  51  and the potentiometer  43  are provided. The left grip  42  is provided with a brake lever  45  for braking the right and left drive wheels  32 R,  32 L.  
         [0038]    The snow removal machine  10  pushes snow forward with the snow removing member  20  to easily clear the snow. Thus it is convenient to use even in a smaller area than an area where the conventional auger-type snow removal machine can work. Further, since the electric motor  51  is employed as a drive source for the crawler belts  31 R,  31 L, the drive mechanism can be made much smaller than in the case where an engine is employed, which results in the more compact snow removal machine  10  as a whole. The snow removal machine  10  of the present invention is thus a compact waking-type snow removal machine, which provides agility and enhanced transportability and operability, reducing labor of the operator.  
         [0039]    Employing the electric motor  51  as a drive source enables much smaller noise than an engine. Accordingly it is possible to use the snow removal machine  10  to remove snow easily at any time during long hours from early morning till night.  
         [0040]    As shown in FIG. 3, the body frame  11  is a pipe frame of a U-shaped pipe material having right and left horizontally extending side members  12 ,  12  with their rear parts inclined upwardly in the rearward direction, and a cross member  13  extending between the rear ends of the side members  12 ,  12 . The right and left side members  12 ,  12  are provided with fork ends  14 ,  14  at the top ends thereof, right and left brackets  15 ,  15  at the front bottoms thereof, and right and left brackets  16 ,  16  at some midpoints of the lengths. The cross member  13  is provided with a bracket  17  in the middle of the width.  
         [0041]    The snow removing member  20  is equipped with a snow removing part  21  detachably mounted to the front of the body frame  11  to push out snow, and guide plates  22 ,  22  in a plate shape mounted to the right and left of the snow removing part  21  to guide snow into the snow removing part  21 . The snow removing part  21  has an arcuate cross section curved projectingly in the rearward direction of the vehicle body in a side view. On the rear surface of the snow removing part  21 , right and left mounting panels  23 ,  23  are provided, which also serve as vertical ribs. The mounting plates  23 ,  23  are attached at their upper parts to the fork ends  14 ,  14  with bolts and nuts  24 ,  24 , and are attached at their lower parts to the brackets  15 ,  15  through right and left mounting arms  25 ,  25  with bolts and nuts  26 ,  26 . The snow removing member  20  is thus detachably mounted to the front of the body frame. The reference numerals  27 ,  27  designate bolts for attaching the guide plates  22 ,  22  to the snow removing part  21 .  
         [0042]    A drive mechanism  50  has a structure into which the electric motor  51  and the power transmission mechanism  60  are integrally incorporated. The drive mechanism  50  has hangers  94 ,  94  on the right and left sides, and are detachably mounted at some midpoints of lengths of the body frame  11  with the top surfaces of the hangers  94 ,  94  laid over the bottom surfaces of the brackets  16 ,  16  and connected to them by bolts and nuts  95 ,  95 .  
         [0043]    [0043]FIG. 4 shows a schematic diagram of the crawler belts, the drive mechanism and the surroundings of the snow removal machine of the present invention.  
         [0044]    In FIG. 4, the power transmission mechanism  60  consists of a first small gear  61  coupled to a motor shaft  52  of the electric motor  51 , a first large gear  62 , a second small gear  63 , a second large gear  65 , a differential gear  66  and right and left drive wheel axles  67 R,  67 L. These members are housed in a case  68 . The first large gear  62  engages with the first small gear  61 , having a larger diameter than the first small gear  61 . The second small gear  63  has a smaller diameter than the first large gear  62 . The first large gear  62  and the second small gear  63  are coupled to rotate in the same direction through an intermediate shaft  64 . The second large gear  65  engages with the second small gear  63 , having a larger diameter than the second small gear  63 . The differential gear  66  is coupled to the second large gear  65 . The right and left drive wheel axles  67 R,  67 L are coupled to the differential gear  66 . Each of the gears  61  to  63  and  65  is a spur gear. To the right and left drive wheel axles  67 R,  67 L, the right and left drive wheels  32 R,  32 L are mounted.  
         [0045]    The differential gear  66  consists of a differential case  71  concentrically mounted to a side surface of the second large gear  65 , a pivot shaft  72  mounted to the differential case  71 , a pair of drive bevel gears  73 ,  73  mounted for idle rotation on the pivot shaft  72 , a pair of right and left driven bevel gears  74 R,  74 L engaging with the drive bevel gears  73 ,  73 , and the right and left drive wheel axles  67 R,  67 L coupled to the driven bevel gears  74 R,  74 L. The pivot shaft  72  extends in a direction perpendicular to the drive wheel axles  67 R,  67 L.  
         [0046]    With the differential gear  66  interposed between the right and left drive wheel axles  67 R,  67 L, power from the electric motor  51  is transmitted through the differential gear  66  and the drive wheel axles  67 R,  67 L to the right and left drive wheels  32 R,  32 L to drive the right and left crawler belts  31 R,  31 L. The direction of rotation of the right and left drive wheels  32 R,  32 L corresponds to that of the motor shaft  52 .  
         [0047]    The right and left rolling wheels  33 R,  33 L are rotatably mounted to a rolling wheel axle  34 .  
         [0048]    The snow removal machine  10  further includes a pair of right and left driving frames  35 ,  35  (See FIG. 3) narrowly extending back and forth, which are disposed inside the right drive wheel  32 R and the right rolling wheel  33 R, and the left drive wheel  32 L and the left rolling wheel  33 L, respectively. Across the rear ends of the driving frames  35 ,  35 , a cross member  36  is extended. The right and left driving frames  35 ,  35  support at their front parts the right and left drive wheel axles  67 R,  67 L, permitting their rotation, and supports at their rear parts the rolling wheel axle  34 , permitting its rotation. Right and left adjusting bolts  37 ,  37  extending from the rolling wheel axle  34  in the rearward direction are fitted to the cross member  36  so that they are adjustable in the back and forth directions. With the adjusting bolts  37 ,  37  adjusted in the back and forth directions, the rolling wheel axle  34  is moved back and forth to adjust the tension of the right and left crawler belts  31 R,  31 L.  
         [0049]    In the figure, the reference numeral  35   a  designates a long hole extending back and forth, and the reference numerals  81  to  86  designate bearings.  
         [0050]    [0050]FIG. 5 shows an enlarged specific sectional view taken along the line  5 - 5  in FIG. 2.  
         [0051]    The case  68  of the power transmission mechanism  60  has a case body  91 , a lid  92  bolted to the case body  91  to block the opening of the case body  91 , a tubular right axle case  93 R bolted to the right end of the case body  91  and a tubular left axle case  93 L bolted to the left end of the lid  92 .  
         [0052]    The electric motor  51  is bolted to the case body  91 . The intermediate shaft  64  is rotatably supported by the case body  91  and the lid  92  through the bearings  82 ,  82 . The right axle case  93 R and the left axle case  93 L are concentrically disposed and house the right and left drive wheel axles  67 R,  67 L. The right and left drive wheel axles  67 R,  67 L are rotatably supported by the right and left axle cases  93 R,  93 L through the bearings  84 ,  84  and  85 ,  85 .  
         [0053]    Right and left brake covers  111 ,  111  are bolted to the top ends of the right and left axle cases  93 R,  93 L. Right and left brake mechanisms  112 ,  112  are mounted to the right and left brake covers  111 ,  111 . Each of the brake mechanisms  112  is a radially expanding drum brake. Each brake mechanism mainly consists of a brake shoe  113  with a brake pad mounted to the brake cover  111 , a cam not shown in the figure for expanding the brake shoe  113  in diameter and a brake drum  114  surrounding the brake shoe  113 . The brake drums  114 ,  114  are mounted to the right and left drive wheel axles  67 R,  67 L. Through the operation of the brake lever  45  as shown in FIG. 2, the brake drums  114 ,  114  on the rotating side are braked with the brake shoes  113 ,  113  on the stationary side through brake cables and cams not shown in the figure, thereby to stop the snow removal machine  10 .  
         [0054]    The drive mechanism  50  is mounted to the body frame  11  by fastening the side members  12 ,  12 , the brackets  16 ,  16  of the side members  12 ,  12  and the hangers  94 ,  94  of the right and left axle cases  93 R,  93 L to each other with bolts and nuts  95 ,  95 . The case  68  is rotatable on the drive wheel axles  67 R,  67 L through the bearings  83 ,  83 . Accordingly the body frame  11  can swing up and down on the drive wheel axles  67 R,  67 L.  
         [0055]    As shown in FIG. 6, the snow removal machine  10  is equipped with an expansion mechanism  120  for permitting the up and down swings of the body frame  11  to adjust the height of the snow removing member  20  as shown in FIG. 1, as well as stopping the up and down swings of the body frame  11  after the adjustment of the height of the snow removing member  20 . The expansion mechanism  120  has a structure in which a hanger  121  on its top end is attached to the bracket  17  with a pivot pin  122  in such a manner that it can swing back and front, and its bottom end is attached to the cross member  36  through a connector bar  123 . The mounting structure of the bottom end of the expansion mechanism  120  will be described later. The connector bar  123  is a long length of member fastened to the cross member  36  with the right and left adjusting bolts  37 ,  37  along the back surface of the cross member  36  between the right and left driving frames  35 ,  35 . In the vicinity of the right grip  42 , a height adjusting lever mechanism  140  that is described later is mounted.  
         [0056]    [0056]FIG. 7 shows details of the mounting structure of the lower part of the expansion mechanism  120  and the adjusting lever mechanism  140  as shown in FIG. 6.  
         [0057]    The mounting structure of the lower part of the expansion mechanism  120  includes a pivot bolt  124  in the middle of the body width of the connector bar  123 . A first bracket  125  is rotatably attached to the pivot bolt  124 . A second bracket  127  is attached to the first bracket  125  so as to be able to rotate up and down through a first pivot pin  126 . A piston rod  153  of the expansion mechanism  120  is screwed at its lower part in the second bracket  127  for attachment, thereby to attach the lower part of the expansion mechanism  120  to the cross member  36  in such a manner that it can swing up and down and rotate from side to side.  
         [0058]    The second bracket  127  has a second pivot pin  131 . A swing arm  132  is rotatably mounted at its base end to the second pivot pin  131 . The swing arm  132  is a moving member extending in such a manner that a push rod  154  protruded downwardly from the piston rod  153  abuts at its bottom end against the swing arm  132 . The swing arm  132  is resiliently biased downwardly with a torsion spring  133  wound on the second pivot pin  131 . The first pivot pin  126  serves as a stopper when the swing arm  132  swings downwardly.  
         [0059]    The height adjusting lever mechanism  140  has an operating lever  143  installed into a case  141  through a shaft  142 . When the operating lever  143  is pushed by the operator&#39;s thumb to rotate in a clockwise direction as shown by an arrow “ru,” an inner wire  145  of a wire cable  144  is pulled. When a releasing lever  147  is pushed to the right, an auto-return mechanism not shown in the figure makes the operating lever  143  automatically come back to the position shown in a solid line from the position shown in a phantom line in the figure. The height adjusting lever mechanism  140  has a structure similar to that of a so-called speed changing lever mechanism mounted to a handle of a bicycle for shifting a speed changing clutch to high speed/low speed.  
         [0060]    The wire cable  144  has a structure in which one end of the inner wire  145  pulled by the operating lever  143  is hooked on a swing tip  132   a  of the swing arm  132 , and one end of an outer tube  146  covering the inner wire  145  is attached to the second bracket  127 .  
         [0061]    [0061]FIGS. 8A and 8B show sectional views showing the structure of the expansion mechanism  120  as shown in FIG. 6. FIG. 8A shows a sectional view of the expansion mechanism  120  in the most extended state. FIG. 8B shows an enlarged sectional view of a part indicated by “b” in FIG. 8A.  
         [0062]    The expansion mechanism  120  has a cylinder  151  with the closed upper end, a tubular piston  152  reciprocatingly movable in the cylinder  151 , a tubular piston rod  153  attached to the bottom end of the piston  152  and extending downwardly, a push rod  154  reciprocatingly movable in the piston rod  153 , a valve element  155  driven by the push rod  154  to move up and down in the piston  152 , a. valve seat  156  provided at the upper end of the piston  152  for opening/closing thereof by motions of the valve element  155 , and a compression spring  157  resiliently biasing the valve element  155  in a direction to block the valve seat  156  by the valve element  155 .  
         [0063]    The combination of the valve element  155 , the valve seat  156  and the compression coil  157  constitutes a valve  158 . The inner space of the cylinder  151  is partitioned off into an upper chamber  161  and a lower chamber  162  by the piston  152  with the lower end of the cylinder  151  closed by an oil seal  159 . The upper chamber  161  and the lower chamber  162  communicate with each other through the valve  158 , the space  163  inside the piston  152  and channels  164 ,  165  formed in the piston  152 . The upper chamber  161  and the lower chamber  162  are filled with a high pressure gas  166  such as a high pressure air. The lower chamber  162  is further filled with an oil  167 .  
         [0064]    In the figures, the reference numeral  171  designates a sliding bearing,  172  designates a cylinder-side stopper,  173  designates a piston rod-side stopper,  174  designates an O ring,  175  designates a boot and  176  designates a nut.  
         [0065]    As shown in FIG. 8A, when the operating lever  143  is in a blocking position P 1  as shown in a solid line, the valve  158  is closed as shown in FIG. 8B. In this state, a high pressure gas  166  cannot pass between the upper chamber  161  and the lower chamber  162 .  
         [0066]    When the operating lever  143  is shifted to a releasing position P 2  as shown in a phantom line so as to pull the inner wire  145 , the swing arm  132  swings upwardly to push up the push rod  154 . The push rod  154  pushes up the valve element  155 , thereby to open the valve  158 . The upper chamber  161  and the lower chamber  162  communicate with each other through the valve  158 , the space  163  and the channels  164 ,  165 . As a result, the high pressure gas  166  can pass between the upper chamber  161  and the lower chamber  162 .  
         [0067]    When the releasing lever  147  is pushed, the operating lever  143  automatically returns from the releasing position P 2  to the original blocking position P 1 . As a result, the swing arm  132  swings downwardly to automatically return to the original position as shown in the figure. The push rod  154  then goes down and the valve  158  is again closed. The high pressure gas  166  cannot pass between the upper chamber  161  and the lower chamber  162 .  
         [0068]    [0068]FIG. 9 shows an explanatory view of the arrangement relationship of components of the snow removal machine according to the present invention.  
         [0069]    In the side view of the snow removal machine  10 , the central position of the right and left drive wheel axles  67 R,  67 L is denoted by “A,” the position of the center of gravity G 1  of the electric motor  51  is “B,” the position of the center of gravity G 2  of the battery  101  is “C,” and the position of the center of gravity G 3  of the control device  105  is “D.” The center of the motor shaft  52  is positioned at B.  
         [0070]    The center of gravity G 1  is positioned at the position B spaced apart by distance L 1  from the position A in the forward direction. The center of gravity G 2  is positioned at the position C spaced apart by distance L 2  from the position B in the backward direction. The center of gravity G 3  is positioned at position D spaced apart by distance L 3  from the position C in the backward direction. In addition, the center of gravity G 1  is positioned at a higher level than the right and left drive wheel axles  67 R,  67 L. The center of gravity G 2  is positioned at a higher level than the center of gravity G 1 . The center of gravity G 3  is positioned at a higher level than the center of gravity G 2 . That is, the electric motor  51  is disposed in such a manner that the motor shaft  52  of the electric motor  51  is positioned forwardly above the center of the right and left drive wheel axles  67 R,  67 L. The battery  101  is disposed behind the electric motor  51 . The charger  103  is disposed behind the battery  101 . The control device  105  is disposed backwardly above the charger  103  (backwardly above the battery  101 ).  
         [0071]    As described above, (1) the electric motor  51  is disposed in such a manner that the center of gravity G 1  of the electric motor  51  of a relatively large weight is positioned in the vicinity of the center of the right and left drive wheel axles  67 R,  67 L, so as to set the distance L 1  smaller; and (2) the position C is set in such a manner that the battery  101  is disposed with the center of gravity G 2  of the battery  101  positioned behind the center of gravity G 1  of the electric motor  51 , and the center of gravity G 2  of the battery  101  is positioned between the center of the rolling wheel axle  34  and the center of the drive wheel axles  67 R,  67 L.  
         [0072]    With the arrangement (1) and (2), the center of gravity of the snow removal machine  10  is positioned forwardly. As a result, the snow removing member  20  can easily plunge into snow, reducing the operator&#39;s workload of removing snow. Further, since the center of gravity of the snow removal machine  10  is biased to the side of the drive wheels  32 R,  32 L, the driving force of the drive wheels  32 R,  32 L on the crawler belts  31 R,  31 L can be fully obtained. Accordingly, the running-through performance of the snow removal machine  10  on snow with the crawler belts  31 R,  31 L is enhanced.  
         [0073]    In addition, in the present embodiment, ( 3 ) the electric motor  51  is positioned in such a manner that the center of the motor shaft  52  is above and ahead of the center of the right and left drive wheel axles  67 R,  67 L (on an inclined straight line L 4 ). The rotational direction R 2  of the drive wheels  32 R,  32 L corresponds to the rotational direction R 1  of the motor shaft  52 , so that the torque acting direction of the drive wheels  32 R,  32 L can be made corresponding to that of the electric motor  51 . When the snow removal machine  10  is propelled, the torque of the electric motor  52  generated in a position above and ahead of the drive wheel axles  67 R,  67 L is effectively utilized, thereby to obtain more sufficient driving force of the drive wheels  32 R,  32 L on the crawler belts  31 R,  31 L. Accordingly, the running-through performance of the snow removal machine  10  on snow with the crawler belts  31 R,  31 L is more enhanced. Further, the snow removing member  20  can more easily plunge into snow, reducing the operator&#39;s workload of removing snow.  
         [0074]    Furthermore, in the present embodiment, (4) the control device  105  is disposed in such a manner that the center of gravity G 3  of the control device  105  is positioned behind the center of gravity G 2  of the battery  101 . Thus the control device  105  is protected from snow damage.  
         [0075]    Now, with reference to FIGS.  9  to  11 , the snow removing function with the snow removal machine  10  as described above will be described.  
         [0076]    [0076]FIG. 9 shows a state where the snow removing member  20  is held up at the highest position. In this state, the expansion mechanism  12  is contracted the most.  
         [0077]    Only when the operating lever  143  of the height adjusting lever mechanism  140  is pushed in the direction of the arrow ru, the high pressure gas inside the cylinder  151  of the expansion mechanism  120  can pass through the piston to the upper or lower side. In this state, when the grips  42 ,  42  are held up, the expansion mechanism  120  is expanded, so that the body frame  11  swings upwardly (in the direction of an arrow “Up”) around the drive wheel axles  67 R,  67 L. As a result, the snow removing member  20  swings downwardly as shown in FIG. 10.  
         [0078]    Thereafter, when the grips  42 ,  42  are held down, the expansion mechanism  120  is contracted, so that the body frame  11  swings downwardly (in the direction of an arrow “Dw”) around the drive wheel axles  67 R,  67 L. As a result, the snow removing member  20  swings upwardly. In this manner, the snow removing member  20  can be adjusted in height.  
         [0079]    When the operating lever  143  is retuned to the original position, the high pressure gas inside the cylinder  151  of the expansion mechanism  120  cannot pass through the piston to the upper or lower side. In this state, the snow removing member  20  can be held at a certain height by blocking the upward and downward swings of the body frame  11 .  
         [0080]    [0080]FIG. 11 shows the state where the snow removing member  20  is held down at the lowest position. In this state, the expansion mechanism  120  is expanded to the full extent.  
         [0081]    As shown in FIG. 11, the snow removal machine  10  is set in such a manner that an extension line El of the body frame  11  passes through the center point E 2  of height H of the snow removing member  20  on a snow removing surface  21   a  of the snow removing part  21  constituting the snow removing member  20  when the grips  42 ,  42  are held up and the body frame is inclined with the front down. At this time, the snow removing member  20  is upright and the bottom surface  20   a  of the snow removing member  20  is positioned below a ground-contacting surface  31   a  of the crawler belts  31 R,  31 L.  
         [0082]    When snow is removed with the snow removal machine  10 , the force f of the snow acting on the snow removing surface  21   a  of the snow removing part  21  of the snow removing member  20  usually acts in a upwardly slanting direction to the rear with respect to the snow removing part  21 . The force f acting on the snow removing part  21  is supported on the shaft center in the longitudinal direction of the body frame inclined in substantially the same direction as that of the force f. Thus the slanting direction of the force f and the body frame  11  is substantially the same, so that no large eccentric load acts on the body frame  11 , eliminating the need to enhance the strength of the body frame  11  more than required, reducing the weight of the body frame  11 .  
         [0083]    Further, when the body frame  11  is inclined with the front down, the center of gravity of the snow removal machine  10  moves to a forward position. Accordingly, the snow removing member  20  can easily plunge into snow Sn, reducing the operator&#39;s snow removing labor. Furthermore, the driving force of the drive wheels  32 R,  32 L on the crawler belts  31 R,  31 L is further enhanced. Accordingly, the running-through performance of the snow removal machine  10  on a road Gr or snow with the crawler belts  31 R,  31 L is further enhanced.  
         [0084]    Now, with reference to FIGS. 12A to  13 B the relationship between the running direction of the snow removal machine  10  and the function of the power transmission mechanism  60  will be described.  
         [0085]    [0085]FIG. 12A shows that the operator walking not shown in the figure holds the grips  42 ,  42  and operates the snow removal machine  10  to run linearly forward, removing snow with the snow removing member  20  pushing out the snow Sn in front. Here, the frictional resistance FR between a road surface and the right crawler belt  31 R is equal to the frictional resistance FL between a road surface and the left crawler belt  31 L in the case of running linearly on a flat road.  
         [0086]    [0086]FIG. 12B shows the power transmission mechanism  60  and the surroundings in the state where the snow removal machine  10  runs linearly as shown in FIG. 12A.  
         [0087]    Power of the electric motor  51  makes the second large gear  65 , the differential case  71  and the pivot shaft  72  rotate in the direction of an arrow “x,” and makes the drive bevel gears  73 ,  73  revolve in the direction of the arrow x, and makes the right and left driven bevel gears  74 R,  74 L, the right and left drive wheel axles  67 R,  67 L and the right and left drive wheels  32 R and  32 L rotate in the direction of the arrow x. As a result, the right and left crawler belts  31 R,  31 L is propelled.  
         [0088]    Since FR=FL, the driving force of the right driven bevel gear  74 R and the driving force of the left driven bevel gear  74 L are the same. Accordingly, the drive bevel gears  73 ,  73  do not rotate on the pivot shaft  72 . The rotational speed NR of the right drive wheel  32 R is equal to the rotational speed NL of the left drive wheel  32 L. Accordingly, the right and left crawler belts  31 R,  31 L have the same running speed.  
         [0089]    [0089]FIG. 13A shows a state where the snow removing member  20  provided at the front of the vehicle pushes out snow Sn while the snow removal machine  10  is turning right, running. At that time, the right frictional resistance FR is larger than the left frictional resistance FL (FR&gt;FL). That is, there occurs difference between the right and left frictional resistances FR, FL.  
         [0090]    [0090]FIG. 13B shows the power transmission mechanism  60  and the surroundings in the state where the snow removal machine  10  is turning right as shown in FIG. 13A.  
         [0091]    The fact FR&gt;FL results in a larger driving force of the right driven bevel gear  74 R than that of the left driven bevel gear  74 L. Accordingly, the right and left drive bevel gears  73 ,  73  rotate about the pivot shaft  72  in directions of arrows y′ and y while revolving in a direction of arrow x. That is, the speed of the left drive wheel  32 L is increased by the amount of the decreased speed of the right drive wheel  32 R of a larger frictional resistance. This provides a rotational difference between the right and left drive wheels  32 R,  32 L to permit the snow removal machine  10  to run smoothly at the time of changing its direction.  
         [0092]    Since the rotational speed NL of the left drive wheel  32 L is larger than the rotational speed NR of the right drive wheel  32 R (NR&lt;NL), the running speed of the left crawler belt  31 L is greater than that of the right crawler belt  31 R. As a result, the snow removal machine  10  can easily turn to the right while running.  
         [0093]    In the case where the snow removal machine  10  is turning to the left while running, FR&lt;FL, which results in the reverse function of the power transmission mechanism  60  of the function at the time of turning right as described above. The running speed of the right crawler belt  31 R is greater than that of the left crawler belt  31 L.  
         [0094]    In summary, the differential gear  66  interposed between the right and left drive wheel axles  67 R,  67 L can absorb the difference in the rotational speeds NR, NL between the right and left drive wheels  32 R,  32 L when the running direction of the walking-type snow removal machine  10  is being changed or corrected. Accordingly, changing direction of the snow removal machine  10  is easy and requires less workload of the operator. Further, since the turning radius can be reduced, the turning performance of the snow removal machine  10  can be enhanced. The easy turning of the snow removal machine  10  enhances its operability and reduces labor. Thus the snow removing workability of the snow removal machine  10  is enhanced.  
         [0095]    In the above embodiment of the present invention, the differential gear  66  may be of any type as long as it absorbs the difference in rotational speeds NR, NL between the right and left drive wheels  32 R,  32 L when the running direction of the walking-type snow removal machine  10  is changed or corrected, not being limited to the specific structure as shown in FIGS. 4 and 5. Further the differential gear  66  may be the one equipped with a limited slip differential.  
         [0096]    Furthermore, the potentiometer  43 , the operating lever  44 , the brake lever  45  and the height adjusting lever mechanism  140  can be disposed on either side of the right and left grips  42 ,  42 .  
         [0097]    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 invention may be practiced otherwise than as specifically described.