GB2137148A - Drive for a Steered Axle of a Vehicle - Google Patents

Abstract

In a vehicle having a steered driven axle 2 and also one or more unsteered driven axles 1, the axles 1, 2 are driven through a differential 23 so that the steered axle 2 can rotate at a different speed from the unsteered one 1 during cornering. Each axle 1, 2 can also have a differential 20, 15 in the usual way to allow the wheels at each end to rotate at different speeds. The differential gear 23 may be driven from a spur wheel in the gearbox and located in a steered axle drive housing 24 which is flange-mounted on the gearbox casing 5. The driving wheels 9, 10 of the differential 23 may have different numbers of teeth, resulting in an unequal division of engine power between the two axles 1, 2. <IMAGE>

Description

SPECIFICATION Drive for a Steered Axle The present invention relates to a drive for a steered axle on a vehicle (which term includes any driven machine) having one or more driven nonsteered axles and at least one driven steered axle with axle-pivot steering.

In the case of vehicles of this kind it is known to drive the steered driven axle from the gearbox by way of gearwheels and a universal-joint shaft.

With this kind of steered axle drive there are disadvantageous effects on the wear on tyres and gearbox parts, the surface of cultivated land, steerability and fuel consumption, because of the different distances travelled by the steered and main axles when negotiating curves.

The present invention seeks to improve the steered axle drive for a vehicle of the type mentioned in such a way that the abovementioned disadvantages are obviated or ameliorated.

According to the invention the steered driven axle on the one hand and the non-steered drive axle on the other are driven via a differential gearing. Preferably the differential gear is mounted beside the gearbox and is driven from the speed-change gearing via a spur wheel.

Preferably the steered axle side of the differential is connected directly or indirectly to a universal joint shaft for driving the steered axle. The nonsteered driven axle may be connected to its side of the differential via a spur wheel gearing.

An embodiment of the invention given by way of example, will now be described with reference to the accompanying drawing, which shows a diagrammatic plan view of a vehicle with an embodiment of the steered axle drive of the present invention.

The vehicle shown in the drawing has a main (un-steered) drive axle 1 and a steered driven axle 2. The engine 3 drives the gearbox situated in the gearbox casing 5 by way of a clutch 4. Arranged in the gearbox is a spur gearhweel 6 which drives a second spur gearwheel 7. Gearwheel 7 is connected securely to the housing 8 of a differential gear 23 which contains two differential drive gearwheels 9 and 10 and also an indefinite number of intermediate wheels 11. One drive wheel 10 drives a universal-joint shaft 12, the pinion 13 and thus the crown gearwheel 14 of the differential gearing 1 5 of the steered driven axle 2. The other drive wheel 9 is connected by a shaft 16 to another spur gearwheel 17 which in turn drives yet another spur gearwheel 18.The spur gearwheel 1 8 is connected fast to the pinion 21 which drives the crown gearwheel 19 and the differential gear 20 of the main drive axle 1. The reduction ratios in the drive axle units 1 and 2 are chosen such that the differential drive wheels 9 and 10 rotate at at least approximately the same speed when the vehicle travels straight ahead.

The spur gearwheel 6 and the spur gearwheel 18 have the same number of teeth. The same applies to the spur gearwheels 7 and 1 7. Thus the spur gearwheel 6 and the spur gearwheel 18 rotate at approximately the same speed when the vehicle travels straight ahead. The spur gearwheel 6 and the spur gearwheel 1 8 can be connected by means of a control claw or dog 22. The differential drive wheels 9 and 10 have different numbers of teeth. This has the result that the engine power is distributed to the two drive axles in accordance with the ratio of these numbers of teeth. In order to accommodate this arrangement it is preferred that the axes of the intermediate wheels 11 are not perpendicular to the axes of the drive wheels 9, 8, 10, but are at a predetermined angle thereto.

The differential drive mechanism, including differential 23 and spur wheels 7 and 17, is contained in a housing 24 mounted by means of flanges on the casing 5 of the gearbox.

1. A drive train for a steered driven axle of a vehicle which additionally has at least one unsteered driven axle, in which the said steered axle and the said unsteered axle are driven respectively from the two sides of a differential gearing arrangement.

2. A drive train according to Claim 1 in which the said differential gearing arrangement is disposed adjacent a gearbox for the vehicle and is housed in a housing mounted on a housing of the gearbox.

3. A drive train according to Claim 2 in which the said differential gearing arrangement is driven by a spur wheel of the gearbox and the said unsteered axle is driven by the differential gearing arrangement via a spur wheel, the said spur wheels being disposed co-axially and rotating at substantially the same speed when the vehicle is moving in a straight line.

4. A drive train according to Claim 3 in which there is provided means to lock releasably the two said spur wheels to rotate with each other and thus lock the said differential gearing arrangement.

5. A drive train according to any one of the preceding claims in which the wheels of the said differential gearing arrangement which drive the said steered and unsteered axles respectively have a different number of gear teeth from each other.

6. A drive train for a steered driven axle substantially as herein described with reference to and as illustrated in the accompanying drawing.

7. A vehicle having a steered driven axle, an unsteered driven axle and a drive train according to any one of the preceding claims.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Drive for a Steered Axle The present invention relates to a drive for a steered axle on a vehicle (which term includes any driven machine) having one or more driven nonsteered axles and at least one driven steered axle with axle-pivot steering. In the case of vehicles of this kind it is known to drive the steered driven axle from the gearbox by way of gearwheels and a universal-joint shaft. With this kind of steered axle drive there are disadvantageous effects on the wear on tyres and gearbox parts, the surface of cultivated land, steerability and fuel consumption, because of the different distances travelled by the steered and main axles when negotiating curves. The present invention seeks to improve the steered axle drive for a vehicle of the type mentioned in such a way that the abovementioned disadvantages are obviated or ameliorated. According to the invention the steered driven axle on the one hand and the non-steered drive axle on the other are driven via a differential gearing. Preferably the differential gear is mounted beside the gearbox and is driven from the speed-change gearing via a spur wheel. Preferably the steered axle side of the differential is connected directly or indirectly to a universal joint shaft for driving the steered axle. The nonsteered driven axle may be connected to its side of the differential via a spur wheel gearing. An embodiment of the invention given by way of example, will now be described with reference to the accompanying drawing, which shows a diagrammatic plan view of a vehicle with an embodiment of the steered axle drive of the present invention. The vehicle shown in the drawing has a main (un-steered) drive axle 1 and a steered driven axle 2. The engine 3 drives the gearbox situated in the gearbox casing 5 by way of a clutch 4. Arranged in the gearbox is a spur gearhweel 6 which drives a second spur gearwheel 7. Gearwheel 7 is connected securely to the housing 8 of a differential gear 23 which contains two differential drive gearwheels 9 and 10 and also an indefinite number of intermediate wheels 11. One drive wheel 10 drives a universal-joint shaft 12, the pinion 13 and thus the crown gearwheel 14 of the differential gearing 1 5 of the steered driven axle 2. The other drive wheel 9 is connected by a shaft 16 to another spur gearwheel 17 which in turn drives yet another spur gearwheel 18.The spur gearwheel 1 8 is connected fast to the pinion 21 which drives the crown gearwheel 19 and the differential gear 20 of the main drive axle 1. The reduction ratios in the drive axle units 1 and 2 are chosen such that the differential drive wheels 9 and 10 rotate at at least approximately the same speed when the vehicle travels straight ahead. The spur gearwheel 6 and the spur gearwheel 18 have the same number of teeth. The same applies to the spur gearwheels 7 and 1 7. Thus the spur gearwheel 6 and the spur gearwheel 18 rotate at approximately the same speed when the vehicle travels straight ahead. The spur gearwheel 6 and the spur gearwheel 1 8 can be connected by means of a control claw or dog 22. The differential drive wheels 9 and 10 have different numbers of teeth. This has the result that the engine power is distributed to the two drive axles in accordance with the ratio of these numbers of teeth. In order to accommodate this arrangement it is preferred that the axes of the intermediate wheels 11 are not perpendicular to the axes of the drive wheels 9, 8, 10, but are at a predetermined angle thereto. The differential drive mechanism, including differential 23 and spur wheels 7 and 17, is contained in a housing 24 mounted by means of flanges on the casing 5 of the gearbox. CLAIMS

1. A drive train for a steered driven axle of a vehicle which additionally has at least one unsteered driven axle, in which the said steered axle and the said unsteered axle are driven respectively from the two sides of a differential gearing arrangement.

2. A drive train according to Claim 1 in which the said differential gearing arrangement is disposed adjacent a gearbox for the vehicle and is housed in a housing mounted on a housing of the gearbox.

3. A drive train according to Claim 2 in which the said differential gearing arrangement is driven by a spur wheel of the gearbox and the said unsteered axle is driven by the differential gearing arrangement via a spur wheel, the said spur wheels being disposed co-axially and rotating at substantially the same speed when the vehicle is moving in a straight line.

4. A drive train according to Claim 3 in which there is provided means to lock releasably the two said spur wheels to rotate with each other and thus lock the said differential gearing arrangement.

5. A drive train according to any one of the preceding claims in which the wheels of the said differential gearing arrangement which drive the said steered and unsteered axles respectively have a different number of gear teeth from each other.

6. A drive train for a steered driven axle substantially as herein described with reference to and as illustrated in the accompanying drawing.

7. A vehicle having a steered driven axle, an unsteered driven axle and a drive train according to any one of the preceding claims.