GB2069655A

GB2069655A - A drive transmission

Info

Publication number: GB2069655A
Application number: GB8003939A
Authority: GB
Original assignee: Curry T I
Current assignee: Curry T I
Priority date: 1980-02-06
Filing date: 1980-02-06
Publication date: 1981-08-26

Abstract

A drive transmission for a toy vehicle comprises an endless belt 10 supported on two spaced rollers 11 and 12 and six intermediate rollers 13 and a drive member 7. Drive member 7 is disposed between, and on the opposite side of the belt 10 to, rollers 11 and 12 such that the belt is held around a portion of the circumference of member 7. Ridges 14 on the member 7 engage in recesses in the belt defined between projections 16 to provide a positive, accurate and efficient drive transmission from a motor connected to the member 7. <IMAGE>

Description

SPECIFICATION A drive transmission The present invention relates to a drive transmission. The transmission is intended primarily, but not exclusively, for use in tracked toy vehicles.

In one such presently known tracked toy vehicle, the drive to the track from the drive motor is transmitted via a sprocket which engages the inner surface of the track. Such an arrangement has been found to be inefficient and to consume excessive amounts of energy and, since these toy vehicles are usually battery operated, this is a distinct and costly disadvantage. To provide for reasonably efficient transmission from the rotatable drive member to the belt, the belt is provided with apertures in which complementary projections on the drive member engage. With this arrangement, any small disalignment of apertures and projections causes jamming of the transmission with possible substantial damage to it. At the very least, the vehicle is out of action for some time and must be carefully serviced to put it back into action.An alternative to this arrangement involves driving the tracks by contact between a rotatable drive member placed in contact and externally of the track near its leading or trailing edge.

According to the present invention, there is provided a drive transmission comprising an endless belt supported on at least two spaced members and a rotatable drive member placed in contact with that surface of the belt opposite to the surface with which the spaced members are in contact and between the spaced members, the rotatable drive member and belt having projections on their contacting surfaces whereby to provide a driving interengagement between them.

A preferred embodiment of the invention may comprise any one or more of the following advantageous features.

(a) The projections on the rotatable drive member comprise ridges extending parallel to the axis of rotation of the member.

(b) The projections on the belt comprise ridges extending transversely to the direction of movement of the belt.

(c) The spaced members comprise rotatable members.

(d) The rotatable drive member is disposed approximately mid-way between the two spaced members.

(e) The rotatable drive member is disposed in relation to the spaced members such that the belt is held in contact with the rotatable drive member around a portion of itsocircum- ference.

(f) Additional rotatable members are disposed within the area defined by the belt in order to define a track.

(g) The belt is made of natural material such as rubber.

(h) The belt is made of synthetic plastics material.

(i) The belt is made of a mixture of natural and synthetic materials.

(j) The members are moulded from natural or synthetic plastics material.

(k) An electrical drive motor is provided for driving the rotatable drive member.

(I) The drive from the drive motor of (k) is through a gearbox.

(m) The drive from the motor of (k) is through a worm gear.

The invention also comprises a vehicle fitted with a drive transmission as defined above.

Under normal circumstances, such a vehicle would comprise two such drive transmissions disposed on opposite sides respectively of the vehicle.

In order that the invention may be more clearly understood, one embodiment thereof will now be described by way of example with reference to the accompanying drawing, in which: Figure 1 shows a side elevational view of a chassis for a tracked vehicle incorporating a drive transmission according to the invention, and Figure 2 shows a plan views of the chassis of Fig. 1.

Referring to the drawing, the chassis comprises a body 1. This body may be moulded from synthetic plastics material or pressed from sheet metal such as mild steel or aluminium. The body comprises a base 2 and opposite side walls 3 and 4. Two tracked drive transmissions 5 and 6 are supported on opposite side walls. Each drive transmission 5, 6 comprises a rotatable drive member 7 connected through a gearbox 8 to an electric drive motor 9. The drive motors 9 are powered by nickel cadmium rechargeable batteries and are radio controlled via a transmitterreceiver link. The receiver and batteries, which are housed in the body 1 are not shown. The gearboxes 8 may be of any suitable form.

Alternatively, worm gears may be used.

Each transmission also includes a belt 10 which serves as the track. Each belt 10 is supported on two upper spaced rollers 11 and 1 2 and a row of six lower rollers 1 3. These rollers are rotatably mounted in the corresponding side wall 3, 4. Each drive member 7 is formed on its external surface with a plurality of ridges 1 4 extending parallel to the axis of rotation 1 5 of the member 7. Similar projections 1 6 are formed all along the external surface of each belt. The projections 1 5 interengage with the recesses defined between the projections 1 6 on the belt to form a driving interengagement.As can be seen from Fig. 1, the positioning of the rotatable drive member 7 in relation to the rotatable spaced members 11 and 1 2 is such that the belt 10 is held around a portion of the circumference of the associated member 7. In this way, a positive, accurate and efficient drive transmission is achieved from the motor 9 to the associated track.

The rollers 11, 1 2 and 1 3 and the drive members 7 may be moulded from synthetic plastics material or may be machined from metal. The belts 10 may be made from natural material such as rubber, or from synthetic plastics material such as nylon. Alternatively, a mixture of natural and synthetic materials or a mixture of different natural materials or a mixture of different synthetic materials may be used. One advantageous form of belt, particularly where the use of the vehicle is heavy, is made of nylon reinforced rubber.

The superstructure of the vehicle will advantageously be provided with a skirt which covers or substantially covers the drive members 7. An additional advantage of placing the drive member 7 effectively in the middle of the vehicle is that ingress of dirt into the drive mechanisms is reduced or eliminated. It will also be appreciated that the use of ridged belts 10 provides a better visual representation of the tracks which corresponding real life vehicles actually have.

Claims

1. A drive transmission comprising an endless belt supported on at least two spaced members and a rotatable drive member placed in contact with that surface of the belt opposite to the surface with which the spaced members are in contact and between the spaced members, the rotatable drive member and belt having projctions on their contacting surfaces whereby to provide a driving interengagement between them.

2. A drive transmission as claimed in Claim 1, in which the projections on the rotatable drive member comprise ridges extending parallel to the axis of rotation of the member.

3. A drive transmission as claimed in Claims 1 or 2, in which the projections on the belt comprise ridges extending transversely to the direction of movement of the belt.

4. A drive transmission as claimed in Claims 1 2 or 3. in which the spaced members comprise rotatable members.

5. A drive transmission as claimed in any preceding Claim, in which the rotatable drive member is disposed approximately mid-way between the two spaced members.

6. A drive transmission as claimed in any preceding Claim, in which the rotatable drive member is disposed in relation to the spaced members such that the belt is held in contact with the rotatable drive member around a portion of its circumference.

7. A drive transmission as claimed in any preceding Claim, in which additional rotatable members are disposed within the area defined by the belt in order to define a track.

8. A drive transmission as claimed in any preceding Claim, in which the belt is made of natural material such as rubber.

9. A drive transmission as claimed in any preceding Claim, in which the belt is made of synthetic plastics material.

1 0. A drive transmission as claimed in any preceding Claim, in which the belt is made of a mixture of natural and synthetic materials.

11. A drive transmission as claimed in any preceding Claim, in which the members are moulded from natural or synthetic plastics material.

1 2. A drive transmission as claimed in any preceding Claim, in which an electrical drive motor is provided for driving the rotatable drive member.

1 3. A drive transmission as claimed in Claim 12, in which the drive from the drive motor is through a gearbox.

1 4. A drive transmission as claimed in Claim 1 2, in which the drive from the motor is through a worm gear.

1 5. A drive transmission substantially as hereinbefore described with reference to the accompanying drawings.