JP3408797B2 - Forward and backward type electric roller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used for carrying in and out of heavy equipment such as semiconductor circuit manufacturing equipment such as steppers, large transformers, large machine tools, air conditioners, and the like.
Further, the present invention relates to a forward-backward moving type electric roller used for transporting articles in various other factories and construction sites.

[0002]

2. Description of the Related Art Conventionally, a carriage having traveling wheels attached to a lower surface of a pedestal has been used for carrying various heavy goods, and the trolley moves along with various heavy goods placed on the pedestal. I will let you. At this time, an electric roller that saves labor by driving and rotating a traveling wheel attached to the bottom surface of the base part with a motor to automatically travel is also used.The electric roller called this electric speed roller is A driving motor is provided inside, and the driving force is appropriately reduced to control the driven wheels to rotate.

[0003]

However, in the electric speed roller provided so far, it is necessary to incorporate a considerably large motor in order to carry a heavy object, which inevitably results in a large apparatus. It has become complicated and difficult to handle. Not only that, but the motor itself uses a commercial 200 volt power source for power, which limits the place of use and is not suitable for use in general small and medium factories, transportation sites, etc. There was an occasion. Further, the clutch mechanism for connecting and disconnecting the drive transmission has a complicated structure and is relatively large in size, and in this respect as well, it is bulky in weight and cumbersome to handle.

In addition, in the conventional turntable that rotatably supports heavy objects, a plurality of steel balls are interposed between the lower surface of the turntable and the upper surface of the top plate of the frame so that the turntable can rotate. However, if multiple steel balls or ring grooves that hold these steel balls are worn over a long period of time and the flatness of the turntable varies, the direction of load changes and the weight There is a problem in that the roller that supports and travels cannot obtain smooth movement, and the carrying capacity is reduced.

Therefore, the present invention has been devised in view of various existing circumstances as described above, and since smooth running can be obtained even if it is used for a long period of time, a commercial power supply of, for example, 100 volts is used. A compact motor that can be used can be adopted as a drive source, and the clutch mechanism, which has a simple structure and is lightweight, can configure the entire device to be lightweight and compact, and to provide a forward-reverse type electric roller that is easy to handle. To aim.

[0006]

In order to achieve the above-mentioned object, in the present invention, a drive wheel 51 and a driven wheel 55 are supported forward and backward, and a frame 2 is provided. The transport source P includes a drive source 10 mounted / disposed, a reduction mechanism 15 for decelerating and outputting the driving force of the drive source 10, and a clutch mechanism 20 for connecting / disconnecting the output from the reduction mechanism 15 to the drive wheels 51. Electric roller 1 for placing and transporting
2, the clutch mechanism 20 is connected to the output shaft of the reduction mechanism 15 and is rotatably supported so as to be integrally rotated. The clutch mechanism 20 is rotatable in the drive clutch 21. , A drive sprocket 25 that is fixed to a clutch shaft 23 that is axially slidably supported and that meshes with the drive clutch 21 so that the drive sprocket 25 is slidable. And the operating means 31 for operating the release of the frame 2. The operating means 31 includes the left and right side walls 7, 8 of the frame 2.
Both sides are rotatably and slidably supported to each other, and the slide shaft 33 having the operation portions 39 at both ends through which the left and right side walls 7 and 8 are inserted is screwed to the slide shaft 33, and is freely rotatable to the drive sprocket 25. And a shifter fork 32 that engages with the shifter fork 32.
The drive sprocket 25 is composed of a compression coil spring 36 that presses and urges the drive sprocket 25 in a direction in which the drive sprocket 25 meshes with the drive clutch 21.

A turntable 6 is attached to a holding shaft 4 which is inserted and held from the lower surface to the upper surface of the top plate portion 3 of the frame 2. The turntable 6 faces the lower surface and the upper surface of the top plate portion 3. Ring grooves 42, 4 formed concentrically
The holding shaft 4 is provided with a pressing force adjusting means 47 that is rotatably held by a plurality of steel balls 44 rotatably mounted on the holding shaft 3, and that adjusts a pressing force for the plurality of steel balls. .

The drive source 10 has a control unit for receiving a signal from an operating unit (78) having a transmitter and for controlling the start and stop of the drive source 10 and the switching of traveling speed and forward and backward movement. There is.

In the forward-reverse type electric roller 1 according to the present invention, when carrying various objects P to be conveyed, the objects P to be conveyed are placed and driven and driven. By this driving traveling, the transported object P is transported to a predetermined place, and the clutch mechanism 2
The direction is changed to the left or right by intermittently switching the driving force at 0, and the control unit that receives a signal from the operation unit of the remote control device 78 having a wireless transmitter starts, stops, and drives the driving source 10. Controls switching between forward and backward movement. At this time, the operating means 31 of the clutch mechanism 20 is operated by rotating the operating portion 39 at any one end of the slide shaft 33 to engage the shifter fork 32 screwed to the slide shaft 33 and engage the drive clutch 21 in the clutch portion. And drive sprocket 25 are engaged with each other to transmit the driving force,
Alternatively, the engagement is released to cut off the driving force. The cutoff of the driving force separates the drive sprocket 25 meshed with the rotating drive clutch 21. At this time, the drive sprocket 25 is compressed by the compression coil spring 36.
Thus, they are pressed and urged in the direction of meshing with the drive clutch 21 via the shifter fork 32, and the meshed state is maintained. Therefore, the slide shaft 33
The drive sprocket 25 is disengaged from the drive clutch 21 by rotating the operating portion 39 at one end of one of the two in a fixed direction and sliding the shifter fork 32 against the compression coil spring 36. On the contrary, when the operation portion 39 of the slide shaft 33 is rotated in the opposite direction, the drive sprocket 25 in the separated state is engaged with the rotating drive clutch 21. At this time, the shifter fork 32 is moved forward. , A sliding force that translates the drive sprocket 25 in parallel with the urging force of the compression coil spring 36, but is not at the position where the meshing teeth of the drive sprocket 25 are tightly engaged with the drive clutch 21 in the meshing clutch portion. Therefore, the meshing is not performed immediately, and the drive sprocket 25 is meshed with the drive clutch 21 by the urging force of the compression coil spring when the meshing teeth are matched next time. The plurality of steel balls 44 that rotatably holds the turntable 6 on the holding shaft, or the ring grooves 42 and 43 that guide the steel balls 44 are rotatably used while supporting a heavy object for a long period of time. However, the wear is accelerated and the turntable 6 is loosened. When the backlash occurs in this way, the adjusting ring 47 as an adjusting means screwed to the holding shaft 4 is provided.
Is rotated by a predetermined angle with respect to the holding shaft 4 and tightened to apply a pressing force to the steel ball 44. When the forward / rearward traveling type electric roller 1 receives a signal transmitted from the operation unit having the wireless transmitter by remote control from the remote control device 78, the traveling / stopping and the switching control of the traveling speed and the forward / backward movement are performed. Done.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the following, one embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 in FIGS. The electric roller 1 is a flat box-shaped frame having a substantially rectangular cross section. A motor, which is a drive source 10, is arranged in the rear portion of the frame 2, and the transmission of the driving force is interrupted by a clutch mechanism 20 formed and arranged substantially in the center portion so that the drive wheel 51 supported in the front portion is rotated. And is adapted to travel in the front-rear direction on the transport surface together with the driven wheel 55 supported on the rear portion.

However, the frame 2 itself is formed of a robust material capable of withstanding and supporting the object P (see FIG. 6) which is a heavy load such as semiconductor circuit manufacturing equipment, large transformers, large machine tools and the like. The turntable 6 is freely rotatable on the front side of the top plate 3, and the holding shaft 4 (details will be described later) inserted vertically from the bottom to the top of the top 3. (See FIGS. 2 to 4). The transported object P placed on the turntable 6
Supports the load by the side portions of the frame 2, and enables relative alignment with the drive sprocket frame 25 in any direction.

The drive source 10 is a small motor driven by a commercial power source of 100 volts, for example, and is mounted between the left and right side walls 7 and 8 in the rear portion of the frame 2. Then, the driving force of the driving source 10 is decelerated and output via the reduction mechanism 15 supported and arranged by the substantially cylindrical gear case 9 fixed to the substantially central portion of the frame 2.

The speed reducing mechanism 15 is connected to a wave generator fixed to an input shaft 16 and has a circular shape in which the input teeth of an elliptical flexspline elastically deformed via a ball are connected to the output shaft. The internal tooth-shaped output teeth of the circular spline are meshed with each other, and the meshing position is moved by the rotating wave generator, resulting in the difference in the number of input teeth of the flexspline and the number of output teeth of the circular spline, and the opposite direction. A so-called harmonic drive that reduces the speed of the circular spline is used. Then, the input shaft 16 is driven to rotate by the transmission chain 17 that hangs around the driving shaft of the drive source 10, and the reduction mechanism 1
By decelerating inside 5 itself, the output is transmitted to the flange washer 18 via the circular spline on the output shaft side.

On the output side of the speed reduction mechanism 15, there is provided a clutch mechanism 20 for connecting and disconnecting the driving force output by speed reduction.
It is installed coaxially with. This clutch mechanism 20
Is rotatably supported by the gear case 9, is fixed to the flange washer 18, and is a cylindrical drive clutch 21 that rotates integrally with the flange washer 18, and is rotatable in the drive clutch 21 and axially. It is fixed to the clutch shaft 23 which is slidably supported,
The drive sprocket 25 is engaged with the drive clutch 21 so that the drive sprocket 25 can be engaged with the drive clutch 21. The drive sprocket 25 is slid, and the operating means 31 is operated to engage or disengage the drive clutch 21.

The drive clutch 21 is integrally fixed to the flange washer 18 by bolts or the like, and the bearing 22 is provided near the opening of the gear case 9.
The flange washer 18 is rotated in the gear case 9 while being supported by the flange washer 18. Further, the clutch shaft 23 is rotatably and rotatably supported between the bearing 24 arranged on the inner side surface of the side wall of the frame 2 and the inside of the drive clutch 21 as shown in the drawing. The drive clutch 21 is formed in a cylindrical shape, and the clutch shaft 23 is supported inside the drive clutch 21 to make the entire structure compact. The drive sprocket 25 fixed to the clutch shaft 23 has a meshing clutch structure and is detachably meshed with the open end of the drive clutch 21. When the meshing is engaged, the drive sprocket 25 is rotated integrally with the drive clutch 21. Rotation is not transmitted by being separated from the drive clutch 21 that is present. Reference numeral 26 in the drawing denotes a needle bearing that rotatably supports the clutch shaft 23 in the drive clutch 21.

Both sides of the operating means 31 are rotatably and slidably supported between the left and right side walls 7 and 8 of the frame 2, and a rotary knob 39 as an operating portion is fixed to both ends through which the left and right side walls 7 and 8 are inserted. A slide shaft 33, a shifter fork 32 that is screwed to a feed screw 38 that is a screw portion formed on one side of the slide shaft 33, and that is rotatably engaged with the drive sprocket 25, and a drive for the shifter fork 32. The sprocket 25 is composed of a compression coil spring 36 that presses and biases the sprocket 25 in the direction in which it engages with the drive clutch 21.

The shifter fork 32 has a substantially U shape when viewed from above (see FIG. 1), and is fitted and engaged with the tooth portion of the drive sprocket 25 rotating in the recess thereof.
As shown in FIGS. 1 and 2, the shifter fork 32 itself supports a slide shaft 33 on the left and right side walls 7 and 8 so as to be positioned in a hanging circuit of a drive chain 50 described later.

In the operation means 31, as shown in FIG. 1, the rotation of the feed screw 38 by operating the rotary knob 39
Screw the shifter fork 32. At this time, when the drive is engaged with the rotating drive clutch 21 and the output is being transmitted, the drive clutch 21 is disengaged. Further, by rotating the rotary knob 39 in the same direction, the shifter fork 32 is moved to the compression coil spring 3.
The drive sprocket 25 is separated from the drive clutch 21 by being slid against the urging force of 6, and the drive force is cut off. Further, when the rotary knob 39 is rotated in the opposite direction, the drive sprocket 2 which is separated from the drive clutch 21 is rotated by the rotating drive clutch 21.
5 is meshed with each other to transmit the drive power, and the shifter fork 32 at this time is slid so as to move in parallel in the direction opposite to the conventional one. This sliding force is urged by the compression coil spring 36 to assist the shifter fork 32 in addition to the sliding by the feed screw 38. By sliding this shifter fork 32, the drive sprocket 25 is attached to the drive clutch 21.
The drive force shall be transmitted by engaging with.

As shown in FIG. 5, the operation of selecting the intermittent driving force by the clutch mechanism 20 is "off" or "on" by the arrow corresponding to the direction of rotation of the rotary knob 39.
Is displayed.

The drive force thus transmitted via the clutch mechanism 20 is transmitted to the roller-shaped drive wheel 51 rotatably supported on the front portion of the frame 2 and is shown in FIG. As described above, the drive wheel 51 is
Drive chain 50 hung between a driven sprocket 52 fixed to the drive sprocket 25 and the drive sprocket 25.
It is designed to be rotationally driven via. Further, the drive wheel 51 supports the load of the conveyed object P together with the roller-shaped driven wheel 55 rotatably supported on the rear portion of the frame 2, and rolls on the conveying surface.

Further, if necessary, the drive wheel 51 and the driven wheel 55 are not limited to the case of being formed into a roller shape suitable for supporting a large load as shown in the drawing, but are arranged on each of the left and right sides of the frame 2. It may be formed in a wheel shape. Then, the turntable 6 for mounting the transported object P on the drive wheels 51.
By arranging, the vehicle is driven and driven at the center position of the load, so that the power traveling performance is excellent.

Reference numeral 61 in the drawing denotes a handle stay for connecting a handle (not shown), and reference numeral 62 denotes a protector projectingly formed so as to prevent damage due to contact with another object, collision or the like. .

Further, the forward-backward moving type electric roller 1 of the present invention
In the following, an embodiment of the support structure of the turntable 6 for mounting and supporting the bottom surface of the transported object P which is a heavy object will be described. As is well known, the turntable 6 includes a plurality of steel balls 44 rotatably interposed in ring grooves 42 and 43 formed concentrically opposite to the lower surface of the turntable 6 and the upper surface of the top plate portion 3. It is rotatably held, and in the turntable 6 of the present invention, a rubber 74 is attached to a support surface on which a heavy object is placed. Therefore, as shown in FIG. 4, the support structure of the turntable 6 according to the embodiment of the present invention has a through hole 41 in the center of the counterbore 40B formed on the back surface of the top plate portion 3 of the frame 2 and a screw on the outer periphery. A holding shaft 4 in which a shaft portion in which 48 is screwed is inserted from the back surface and a flange portion 45 is inserted in the counterbore 40B, and the upper end of the shaft portion of the holding shaft 4 is formed at the center of the turntable 6 for insertion. Formed fitting hole 75, a counterbore hole 76 formed on the outer periphery of the fitting hole 75 on the back surface of the turntable 6, and a stepped portion of the holding shaft 4 which can be inserted into the counterbore hole 76 and which is on the inner periphery. An adjusting ring 47 serving as a pressing force adjusting means, in which a female screw that can be screwed into a screw 48 formed on the outer periphery of the screw 49 is formed, and six through screw holes are formed on the same circumference in the center of the upper surface, The adjustment lever inserted in the counterbore hole 76 on the back of the table 6 Consisting the plurality of bolts 72 screwed in through the screw holes 6 uniformly arranged in grayed 47 from the turntable 6 top.

The turntable 6 constructed as described above
The assembling procedure and adjusting method will be described. First, the holding shaft 4 in which a screw 48 is screwed around the through hole 41 in the center of the counterbore 40B formed on the back surface of the top plate portion 3 of the frame 2.
Insert the flange portion 45 into the counterbore 40B by inserting the shaft portion from the back side, and screw the adjusting ring 47 into the screw 48 on the outer periphery of the inserted shaft portion so that the bottom surface of the adjusting ring 47 is the top surface of the top plate portion 3. On the other hand, adjust so that a minute gap is formed. next,
A plurality of steel balls 44 are arranged and held in a plurality of ring grooves 42 formed on the top surface of the top plate 3 concentrically, and a plurality of ring grooves formed on the rear surface of the turntable 6 corresponding to these ring grooves 42. 43 is fitted and supported on the steel ball 44 in the ring groove 42. At the same time, turntable 6 countersunk hole 7 on the back
The bottom surface 46 of the holding shaft 4 is fitted into the shaft hole of the holding shaft 4 in the fitting hole 75 at the center of the turntable 6 until it comes into contact with the stepped portion 49 of the holding shaft 4, and the adjustment ring 47 is inserted into the counterbore hole 76. Fit the upper surface of the adjustment ring 47 with a counterbore 76 Bottom surface 46
The bolts 72 inserted from the upper surface of the turntable 6 are screwed into the screw holes, which are evenly arranged in the adjusting ring 47, in a state of being closely attached to the.

Here, when the turntable 6 is used for a long period of time and a plurality of steel balls 44 and ring grooves 42, 43 are worn, the six bolts 72 are removed to hold only the adjustment ring 47. Α around the screw 48 on the outer circumference of the shaft of No. 4
(60 ° in the present embodiment), for example, when the adjustment ring 47 is screwed again with the bolt 72 after advancing the screw pitch 1.5 / 6 = 0.25 mm, the upper surface of the adjustment ring 47 and the bottom surface of the counterbore hole 76 are separated. A small gap S (0.25
mm) is formed, and the turntable 6 is moved to the side of the top plate 3 by 0.25 mm, so that the tightening margin of the bolt 72 is secured, and the pressing force is applied to the steel ball 44 by tightening the bolt 72. You can Therefore, even when a plurality of steel balls or ring grooves for holding these steel balls are worn for a long period of time and the holding force of the turntable 6 is reduced,
By appropriately adjusting the pressing force of the turntable 6 against the steel balls 44 by the adjusting ring 47, smooth running can be ensured for a long period of time.

The present invention is configured as described above,
An example of use of the electric roller 1 will be described. As shown in FIG. 6, for example, various large and heavy conveyed objects P
The electric roller 1 is arranged on the front part under the bottom surface of the electric roller 1 so that the left and right side casters 80 for preventing fall are arranged on the left and right sides of the electric roller 1, and the left and right are interlocked. The rear part of the transported object P is supported by the remote-controlled steered electric steering roller 90 configured as described above. By operating and controlling the electric roller 1 by the remote control device 78 and operating and controlling the electric steering roller 90 by another remote control device 91 in such a state, the drive source (10) is started, stopped, and traveling speed and forward and backward movement. The transfer control is performed to move and convey the sheet.

Further, as shown in FIG. 7, the electric rollers 1 are arranged at the four corners of the bottom surface of the object P to be conveyed, and when the object P is conveyed, the electric rollers 1 of the present invention arranged, for example, on the left and right of the front part are driven. The source (10) receives a signal from a remote control device 78 or the like as an operation unit having a wireless transmitter to control the start and stop of the drive source (10) and the switching of traveling speed and forward / backward movement. Therefore, it is to be moved and transported.

[0028]

The present invention is configured as described above, and therefore, a miniaturized motor can be adopted as the drive source 10 and the whole device is constituted by the clutch mechanism 20 having a simple structure and a light weight. Can be configured to be lightweight and small, and can be easily handled, and in particular, even a large-sized transported object P that is heavy in weight can be easily transported.

Particularly, since the holding shaft 4 is provided with the adjusting ring 47 as a pressing force adjusting means for adjusting the pressing force with respect to the plurality of steel balls 44 which rotatably holds the turntable 6, it is a heavy load. A plurality of steel balls 44, which are used for carrying in and out of the non-conveyed goods P, installation, and also for transporting articles at various other factories and construction sites, and for supporting heavy-weight objects for a long period of time to support the turntable 6, Even if the ring grooves 42, 43 holding the steel balls 44 are worn and the holding force of the turntable 6 is reduced, the turntable for the steel balls 44 is appropriately adjusted by the adjusting ring 47 as the pressing force adjusting means of the holding shaft 4. By adjusting the pressing force of 6, smooth running can be secured for a long time.

Further, according to the present invention, the drive wheel 51 and the driven wheel 55 are provided.
A front and rear frames 2, a drive source 10 arranged in the frame 2, a speed reduction mechanism 15 for decelerating and outputting the driving force of the frame 2, and a clutch mechanism 20 for intermittently connecting the deceleration output to the drive wheels 51. And a clutch mechanism 20.
Is a cylindrical drive clutch 21 that is rotatably supported so as to be integrally rotated by being connected to the output shaft of the reduction mechanism 15, and is rotatable in the drive clutch 21 and axially. A drive sprocket 25 that is fixed to a clutch shaft 23 that is slidably supported and that engages with the drive clutch 21 in a freely engageable manner.
And the operating means 31 for sliding the drive sprocket 25 to engage with or disengage from the drive clutch 21, the clutch mechanism 20 can be arranged coaxially with the reduction mechanism 15 and is small and lightweight. By operating with certainty, the entire device can be made compact.

Further, the operation means 31 of the clutch mechanism 20 can be easily operated from outside the frame 2, the operability is good, and the handling is easy.

In addition, for the traveling operation of the forward / backward movement type electric roller 1, by using the remote control device 78, the signal transmitted from the operation unit having the radio transmitter is received, and the electric roller is moved or stopped. , And traveling speed and forward / backward switching control can be operated even from a distant position, and operability is improved.

[Brief description of drawings]

FIG. 1 is a plan cross-sectional view of a forward / backward moving type electric roller.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

4A is a partially enlarged cross-sectional view showing a turntable support structure, and FIG. 4B is a CC cross-sectional view of FIG. 4A.

FIG. 5 is a perspective view of a forward and backward electric roller.

FIG. 6 is a perspective view of a use state during transportation of a transported object.

FIG. 7 is a perspective view of a usage state during transportation of a transported object in another usage example.

[Explanation of symbols]

1 ... Forward / backward type electric roller 2 ... Frame 3 ... Top plate 4 ... Holding shaft 6 ... Turntable 7, 8 ... Left and right side walls 9 ... Gear case 10 ... Motor (driving source) 15 ... Reduction mechanism 16 ... Input shaft 17 ... Transmission chain 18 ... Flange washer 20 ... Clutch mechanism 21 ... Drive clutch 22 ... Bearing 23 ... Clutch shaft 24 ... Bearing 25 ... Drive sprocket 31 ... Operation means 32 ... Shifter fork 33 ... Slide shaft 36 ... Compression coil spring 38 ... Feed screw 39 ... Rotating knob (operation section) 40B ... Hole 41 ... Through holes 42, 43 ... Ring groove 44 ... Steel ball 45 ... Flange portion 46 ... Bottom surface 47 ... Adjustment ring (pressing force adjusting means) 48 ... Screw 49 ... Stepped portion 50 ... drive chain 51 ... drive wheel 52 ... driven sprocket 55 ... driven wheel 72 ... bolt 74 ... rubber 75 ... fitting Dowel hole 76 ... Counterbore hole 78 ... Remote control device 80 ... Fall prevention caster 90 ... Electric steering roller 91 ... Remote control device P ... Conveyed object S ... Minute gap

Claims (3)

(57) [Claims] 1. A frame in which driving wheels and driven wheels are supported in front and rear, and arranged, a drive source mounted and mounted in the frame, a reduction mechanism for decelerating and outputting a driving force of the drive source, and In an electric roller that has a clutch mechanism that connects and disconnects the output from the speed reduction mechanism to the drive wheels, and that mounts and conveys an object to be conveyed, the clutch mechanism is linked to the output shaft of the speed reduction mechanism and integrally rotated. And a cylindrical drive clutch that is rotatably supported, and is rotatable in the drive clutch and fixed to a clutch shaft that is axially slidably supported and can be engaged with the drive clutch. A drive sprocket that meshes with the drive sprocket, and an operating means that slides the drive sprocket to engage or release the engagement with the drive clutch. The working means is a slide shaft having both sides rotatable and slidably supported between the left and right side walls of the frame and provided with operation portions at both ends through which the left and right side walls are inserted, and the slide shaft is screwed into the slide shaft to rotate the drive sprocket. A forward-reverse type electric roller comprising a shifter fork that freely engages and a compression coil spring that presses and biases the shifter fork in a direction in which a drive sprocket meshes with a drive clutch. 2. A turntable is attached to a top plate portion of the frame by a holding shaft which is inserted and held from a lower surface to an upper surface, and the turntable is concentrically provided so as to face the lower surface and the top surface of the top plate portion. A holding shaft is rotatably held by a plurality of steel balls rotatably mounted in the formed ring groove, and a holding force adjusting means is provided on the holding shaft for adjusting a pressing force with respect to the plurality of steel balls. The forward-backward moving type electric roller according to claim 1. 3. The drive source has a control unit that receives a signal from an operation unit having a wireless transmitter and controls start and stop of the drive source and switching of traveling speed and forward and backward movement. Forward-and-backward type electric roller described.