GB2249607A - Transmission - Google Patents

Abstract

A transmission having a casing 2 comprising two casing parts 4 and 6 which are connected together for relative pivotal movement about a hinge axis A, an input transmission element 10 being mounted in one of the casing pans 4 or 6, and an output transmission element 14 being mounted in the other casing part (4 or 6), the input and output transmission elements being interconnected for drive by an intermediate transmission element (20) which is rotatable about the hinge axis A. In a preferred embodiment of the present invention, the transmission elements are gears and a motor 8 for driving the gears is housed in one of the casing parts. Such a transmission is suitable for rotating a cupola 90 in a military vehicle, e.g. a tank. <IMAGE>

Description

TRANSMISSION This invention relates to a transmission, and particularly, although not exclusively, to a transmission for transmitting drive to a rotatable cupola provided on a vehicle, aircraft or vessel, or for rotating a telescope or radar dish.

To rotate the cupola of a tank it is known to mount a drive unit, comprising a motor and a transmission, within the cupola, with an output pinion of the transmission engaging a toothed drive ring fastened to the hull of the tank.

In such a system, accurate meshing between the output pinion and the drive ring is vital to ensure that a gun mounted in the cupola can be correctly and reliably aligned with its target. In addition, the space occupied by the drive unit, which rotates with the cupola, must be minimised to allow room for other equipment, and to avoid collisions with personnel in the tank.

According to the present invention there is provided a transmission having a casing comprising two casing parts which are connected together for relative pivotal movement about a hinge axis, an input transmission element being mounted in one of the casing parts, and an output transmission element being mounted in the other casing part, the input and output transmission elements being interconnected for drive by an intermediate transmission element which is rotatable about the hinge axis.

A liquid tight seal is preferably provided between the first and second casing parts, for example comprising a flexible gaiter connected between them.

Locking means may be provided for locking the input element relatively to the casing when drive is not being transmitted.

In a preferred embodiment, the hinge axis is defined by a shaft which supports the intermediate transmission element and is itself rotatably supported by both casing parts.

Preferably, the transmission elements are gears.

A motor for driving the transmission elements may be secured to one of the casing parts, and an overload clutch may be interposed at any point between the motor and the transmission.

In a preferred embodiment, at least one of the transmission elements is accessible through an opening in the casing for engagement with, for example, a ring gear.

For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a sectioned side view of a drive unit; Figure 2 is a fragmentary view of a detail of the unit of Figure 1; Figure 3 is a view in the direction of the arrow III in Figure 1; and Figure 4 is a schematic view showing the drive unit in use.

The drive unit shown in Figure 1 comprises a gear transmission accommodated in a casing 2, and a motor 8. The casing 2 comprises two casing parts 4 and 6.

The casing parts are connected together for relative pivotal movement about a hinge axis A.

The motor 8 is secured to the first casing part 4.

This motor 8 drives an input gear 10, also mounted in the first casing part 4, through an overload clutch 12.

An output gear 14 and a high reduction ratio gear assembly 16 are mounted in the second casing part 6.

The input gear 10 is permanently interconnected for drive with a gear 18 on the input side of the high reduction ratio gear assembly 16, by means of an intermediate gear 20, and the gear 18 is permanently interconnected for drive with the output gear 14, through the high reduction ratio gear assembly 16.

With this arrangement, drive from the motor 8 can be transmitted to the output gear 14, whilst allowing relative pivotal movement of the casing parts 4 and 6 about the hinge axis A.

The housing of the motor 8 is accommodated partially within the first casing part 4, and has a flange 22 secured to the first casing part by bolts 24.

An output shaft 28 of the motor 8 is keyed to a hollow drive element 30, which is supported in the first casing part by a ball bearing 32. The clutch 12 provides a driving connection between the drive element 30 and the input gear 10. A first clutch part 42 of a dog clutch 44 is non-rotatably fixed to the free end 46 of the hollow drive element 30. This first clutch part 42 can engage with a second clutch part 48.

A rod 50 is rotatably mounted within the free end 46 of the hollow drive element 30 and projects along the axis of the motor into the top (as viewed in Figure 1) of the first casing part 2. The outer surface of the rod 50 is provided with splines 49 which engage the first casing part 4 to prevent rotation of the rod 50, while allowing it to move lengthwise.

The second clutch part 48 is mounted on the rod 50 and is provided with splines which engage with the splines on the outside surface of the rod 50 and prevent rotation of the second clutch part 48.

The lower end of the second clutch part 48 abuts a flange 52, which projects from the rod 50. A return spring 54 biases the second clutch part 48 towards the flange 52.

The second clutch part 48 has a flange 56 which is adjacent to an electromagnetic coil 60.

The rod 50 is provided with a slot 63 at its end furthest from the hollow element 30. A part of the slot extends obliquely to the axis of the rod 50. A pin 62 engages with the slot 63 and is attached to a handle 66 which is rotatably mounted on the first casing part 4.

The first casing part 4 is connected to the second casing part 6 for relative pivotal movement about the axis A. This connection is achieved by hinge pins 72 and 76. The casing parts 4 and 6 have respective oppositely disposed faces 78, 80 (Figure 3). The casing part 4 has two lugs 82, 84 projecting from the face 78, and the casing part 6 has two lugs 86, 88 projecting from the face 80. The lugs 82, 84, 86, 88 have cylindrical bores 90, all of which, when the casing 2 is assembled, are aligned with the axis A, and receive the common hinge pin 72. The hinge pin 72 also serves as the supporting shaft for the intermediate gear 20, which is mounted on the pin 72 by means of a needle roller bearing 91.

The hinge pin 76 is received in cylindrical bores 92, 94 in lugs 96, 98 projecting from the respective faces 78,80 at a position away from the hinge pin 72.

Shims 79 ensure correct spacing between the lugs 82, 84, 86, 88, 96 and 98. Bearings 80 are provided between the hinge pins 74 and 76 and their cylindrical bores to reduce friction in the hinge.

As shown in Figure 3, to prevent lubricant from flowing from the casing 2 at the hinge 70, and to prevent the ingress of contaminants, a flexible gaiter 99, in the form of a bellows, is provided. The gaiter 99 extends between the faces 78, 80 and entirely surrounds the hinge pin 74.

By way of example, the drive unit shown in Figures 1 to 3 may be used to rotate the cupola or gun turret of a tank (see Figure 4). For this purpose the first casing part 4 would be fixed to the inside of the cupola 100. The casing part 6 has an opening providing access to the output gear 14 which is aligned with a ring gear 102 secured to the hull 104. Meshing between the output gear 14 and the ring gear 86 can be adjusted accurately by pivoting the second casing part 6 to take the output gear 14 towards or away from the ring gear 86. When adjustment is complete, the second casing part 6 may be firmly bolted in place relative to the first casing part 4.

To rotate the cupola, power is suplied to the motor 8. At the same time, the coil 60 is energized, and causes the first clutch part 42 of the dog clutch 44 to be raised, disengaging the dog clutch 44 and allowing the hollow element 30 to rotate. Drive is transmitted through the clutch 12 to the input gear 10 and then to the output gear 14 via the intermediate gear 20 and high reduction ratio gear assembly 16. In the embodiment described, the output gear 14 meshes with the ring gear 102 in the hull 104 of the tank, so that rotation of the output gear 14 causes the cupola 100 to rotate. When the direction of rotation of the motor 8 is reversed the cupola 100 rotates in the other direction.

If load on the clutch 12 becomes excessive, due for instance to obstruction of the cupola 100, the clutch 12 will slip, preventing damage.

Once the desired degree of rotation has been achieved the coil 60 is deactivated and the dog clutch engages to prevent rotation of the hollow drive element 30, so that the cupola 100 is locked in position relative to the hull 104 of the tank.

The ability of the two parts 4 and 6 of the casing 2 to pivot relatively to each other enables accurate adjustment of the meshing of the output gear 14 with the ring gear 102, both when initially installing the drive unit, and during maintenance. Thus backlash and excessive wear can be avoided in a simple manner.

In some circumstances, for example if the power supply to the motor 8 fails, it is necessary to rotate the cupola manually. This is done by a separate winding mechanism (not shown). For manual operation, the dog clutch 44 is disengaged manually by rotating the handle 66. This causes the rod 50 to rise as the pin 62 rides along the angled slot 63, causing the second clutch part 48 of the dog clutch 44 to be lifted out of engagement with the- first clutch part 42.

Claims (10)

1. A transmission having a casing comprising two casing parts which are connected together for relative pivotal movement about a hinge axis, an input transmission element being mounted in one of the casing parts, and an output transmission element being mounted in the other casing part, the input and output transmission elements being interconnected for drive by an intermediate transmission element which is rotatable about the hinge axis.

2. A transmission as claimed in claim 1, in which there is a liquid tight seal between first and second casing parts.

3. A transmission as claimed in any one of the preceding claims in which the transmission elements are gears.

4. A transmission as claimed in any one of the preceding claims in which locking means is provided for locking the input element relatively to the casing.

5. A transmission as claimed in any one of the preceding claims in which the hinge axis is defined by a pivot shaft which supports the intermediate transmission element.

6. A transmission as claimed in any one of the preceding claims in which a motor for driving the transmission elements is secured to one of the casing parts.

7. A transmission as claimed in any one of the preceding claims in which an overload clutch is housed in one of the casing parts.

8. A transmission as claimed in any one of the preceding claims in which at least one of the transmission elements is accessible through an opening in the casing.

9. A transmission substantially as described herein, with reference to and as shown in the accompanying drawings.

10. A vehicle having a rotatable cupola, and a transmission as claimed in any one of the preceding claims for transmitting drive to the cupola.