Angle gear for vehicle steering mechanism

An angle gear for a vehicle steering mechanism includes two bevel gears which can be axially displaced in a housing in order to adjust the rotation backlash of the gear. The axes of the bevel gears form an angle relative to each other and are connected, respectively, to a shaft leading to the steering shaft and a shaft leading to the steering mechanism on the vehicle axle. Axial motion away from the intersection of the shaft axes, which would increase the backlash, is prevented by thrust bearings supported against the housing. Axial motion in the other direction is secured against by means of shackle with spherical cup bearing surfaces that bear against the end faces of the bevel gears, which shackle is adjustable to compensate for the manufacturing tolerances of the bevel gears.

BACKGROUND OF THE INVENTION 
The invention concerns an angle gear for a vehicle steering mechanism with 
bevel gears which can be axially displaced in a housing and whose axes 
form an angle with each other. 
It is frequently necessary, particularly in vehicles with controlled axles 
arranged essentially below the passenger compartment, e.g., in small goods 
carriers and buses designed as front wheel drive vehicles, to insert an 
angle gear into the steering mechanism. This angle gear transmits the 
steering movement from the steering shaft, which suitably extends towards 
the front and bottom of the vehicle with an inclination, to the shaft 
leading to the steering mechanism arranged on the controlled axle. 
In order to ensure the quality of such angle gears, it is necessary to 
adjust the bevel gear pairs of these angle gears that mesh with each 
other, with the smallest possible rotation backlash. On the other hand, 
such rotation backlash must not be eliminated in its entirety because in 
such a case there would arise the danger of the tooth flanks squeezing 
each other during rotation of the gears. Such an adjustment of the 
rotation backlash of the bevel gears to the smallest possible values may 
be obtained by the insertion of correspondingly dimensioned spacers or 
thrust washers between the housing of the angle gear and the bevel gears. 
As a result, the bevel gear shafts must be axially adjustable in 
opposition to the forces that occur during a steering operation, i.e. in 
the direction towards the intersection of the axes of the two shafts. Such 
axial adjustability of the bevel gear shafts, however, is disadvantageous 
in that in case of a load on the bevel gears in opposition to the forces 
generated during steering, e.g. due to axial stress on the steering shaft 
or distortions of the vehicle frame, the bevel gears are still axially 
stressed in the direction towards elimination of all rotation backlash, 
with all the detrimental consequences resulting therefrom. 
SUMMARY OF THE INVENTION 
It is the purpose of the present invention to create an angle gear 
including bevel gears for use in the steering mechanism of a vehicle, 
wherein an axial displacement of the bevel gear shafts, due to stresses 
occuring during operation and in opposition to the tooth forces originated 
by the steering moments, can be easily avoided, in spite of a favorable 
adjustability of the gear rotation backlash. 
This purpose is attained in accordance with the invention in that a support 
arrangement with bearing surfaces directed essentially perpendicular to a 
line between the end faces of the bevel gears and bearing against them on 
the housing, is maintained for axial support of the gears. It is useful if 
the support arrangement is designed for infinitely variable compensation 
of axial tolerance variations of the bevel gears. In accordance with a 
further refinement of the invention, the bearing faces may be provided 
with a spherical cup-like surface and a coating, e.g., of a material that 
decreases wear and tear. 
A preferred form of embodiment of the invention provides that the support 
arrangement comprises a shackle having the bearing surfaces and being 
adjustably fastened on two lateral support surfaces of the housing by 
means of fastening screws. The shackle extends essentially perpendicular 
to the line bisecting the angle between the bevel gear axes. Adjustability 
of the shackle is obtained in that the shackle is provided with 
longitudinal slots for passage of the fastening screws, said slots being 
suitably curved in the form of a circular arc so that favorable guiding of 
the shackle is obtained. The fastening screws may be secured against 
loosening in that an assembly opening of the housing, concentric with the 
angle bisecting line of the bevel gear axes, can be closed by a lid 
provided with a circular ring collar that bears against the radially outer 
key faces of the fastening screws. 
The angle gear, in accordance with the invention, makes it possible to 
adjust the bevel gears relatively simply and precisely in the axial 
direction that reduces rotation backlash to as small a value as possible, 
either by inserting thrust washers of different thicknesses between the 
housing of the angle gear and the bevel gears, or by machining the stop 
faces of the housing in conformity with the precisely measured bevel gears 
to be installed. The axial adjustability of the bevel gears is eliminated, 
following setting of the rotation backlash, by fixing the support 
arrangement on the housing of the angle gear in accordance with the 
invention. The support arrangement is then adjusted in such a manner that 
the bearing faces it contains act directly on the end faces of the bevel 
gears, which are designed as thrust surfaces, so as to secure them in 
their axial position. In particular, the bevel gears are secured against 
such forces as are directed in opposition to the tooth forces generated in 
the bevel gears during the steering operation.

DESCRIPTION OF A PREFERRED EMBODIMENT 
In the drawing an angle gear which is provided for the steering of a front 
wheel drive vehicle has a housing 1. A shaft 2 is provided with a bevel 
gear 4 of the angle gear and is connected with a steering shaft, not 
shown. A shaft 3 provided with another bevel gear 5 leads to the steering 
mechanisms of the vehicle, likewise not shown, on the axle of the vehicle. 
The axes of the shafts 2 and 3 intersect at an angle which, in the example 
represented here, is less than 90.degree.. The shafts 2 and 3 are 
supported in needle roller bearings 9 and 11 whose outer races 8 and 10 
are maintained in bores 6 and 7 of the housing 1. Seals 12 are provided in 
the bores on the side walls remote from the bevel gears. They are secured 
in the axial direction by means of caulkings or wedgings 13 provided at 
the end face of the housing and distributed over the periphery of the 
bores. 
Between bearings surfaces 14 and 15 of the housing and rear end faces 16 
and 17 of the bevel gears 4 and 5 associated therewith, there are provided 
thrust washers 18 and 19. These washers may possibly have various 
thicknesses for the purpose of compensating tolerance deviations of the 
bevel gears and for adjusting the rotation backlash of the bevel gears. 
However, it is also possible to separately machine the bearing surfaces 14 
and 15 of the housing 1, with the help of automatic machining devices, 
after the bevel gears to be assembled in the pertinent housings have been 
measured, so that following insertion of a thrust washer having a constant 
thickness, a predetermined rotation backlash is attained. As a result, the 
bevel gears 4 and 5 are secured axially in one direction. 
In order to obtain a support of the bevel gears in the other direction 
also, thereby excluding an elimination of the small backlash provided, 
e.g. due to forces created during operation and extending in the direction 
toward the intersection of the shaft axes, a shackle 20 is provided for 
support. It is fastened adjustably by means of two fastening screws 27 on 
lateral bearing surfaces 28 and 29 of the housing 1. The adjustment is 
obtained in that on the shackle 20 there are provided longitudinal slots 
31 extending in the shape of a circular arc and through which pass the 
fastening screws 27 in order to be secured in the threads 30 on the 
support faces 28 and 29. The support faces 28 and 29 are essentially 
perpendicular to the angle bisecting line 36 of the axes of the shafts 2 
and 3 so that the shackle 20 is also placed in the same plane. Bearing 
elements 21 and 24 are fastened in the manner of rivets to the shackle. 
These elements bear, by way of bearing surfaces 22 and 25 which are shaped 
like spherical cups, against the end faces 23 and 25 of the bevel gears 4 
and 5, which faces are designed as thrust surfaces. Faultless application 
of the bearing elements 21 and 24 against the end faces 23 and 26 of the 
bevel gears 4 and 5, whose positions may differ because of tolerance 
variations in the manufacture of the bevel gears 4 and 5, is obtained as a 
result of the adjustability of the support shackle 20. The adjustability 
is achieved because the shackle can be displaced within the limits defined 
by the circular arc longitudinal slots 31 and can be adjusted during 
assembly of the angle gear in such a manner that the bearing elements 21 
and 24, which are directed essentially perpendicular to the end faces of 
the bevel gears, are applied against the associated end faces. After the 
fastening screws 27 have been tightened, they are secured against 
loosening in that a lid 33 introduced into an assembly opening 32 of the 
housing 1 has its ring collar 34, located radially outward relative to the 
center axis 36, bear against the key faces 35 of the fastening screws 27. 
The ring collar is shown in FIG. 2 in dots and dashes for the sake of 
simplicity. FIG. 2 illustrates the application of this ring collar against 
the key faces. 
The angle gear in accordance with the invention is assembled by initially 
introducing the outer races 8 and 10 of the bearings 9 and 11 into the 
corresponding bores 6 and 7 of the housing 1 and securing them axially by 
a collar on the side facing the assembly opening. Thereafter, the shafts 2 
and 3, provided with the thrust washers 18 and 19, but not with the 
bearings 9 and 11, are threaded in. Subsequently, the bearings 9 and 11 
are slid in from the side of the bores 6 and 8 opposite the assembly 
opening 32 and, following assembly of the sealing rings 12, are secured 
axially together with the rings by means of caulking 13. Following this, 
the support shackle 20 is placed on the bearing surfaces 28 and 29 of the 
housing 1 and is secured by the fastening screws 27 which had been 
threaded in loosely. The fastening screws are tightened only after a 
corresponding rotation of the shackle 20 has caused the bearing elements 
21 and 24 with their bearing faces 22 and 25 to apply themselves 
simultaneously against the end faces 23 and 26 of the bevel gears 4 and 5, 
whereby the smallest possible axial clearance is to be observed. Finally, 
the lid 33 is introduced into the assembly opening 32 so that the ring 
collar 34 bears against the radially outside, relative to the center axis 
36, key faces of the fastening screws 27, whereby the fastening screws are 
secured against being turned so as to loosen them.