Pivot assembly for a vehicle cab

An agricultural or industrial utility vehicle includes a vehicle body, an operator's platform and a pivot assembly, by means of which the operator's platform can be pivoted on the utility vehicle about an essentially horizontal pivot axis. The pivot assembly includes at least two guide arms of differing lengths and/or extending in non-parallel directions. Each guide arm has one end which is coupled at a joint to the operators platform and another end which is coupled at another joint to the vehicle body. The connecting joint axes of the guide arms are essentially parallel to each other and are spaced apart from each other. Such a pivoted operator's platforms permits access for maintenance, repair or cleaning of vehicle components which are arranged under the operator's platform.

BACKGROUND OF THE INVENTION 
This invention relates to an agricultural or industrial utility vehicle 
with a vehicle body, an operator's platform and a pivot assembly which 
pivotally couples the platform to the vehicle so that the platform can be 
pivoted about an essentially horizontal pivot axis. 
Operator's platforms (with or without cab) can be installed on agricultural 
or industrial utility vehicles so as to be pivoted or removable, in order 
to permit access for purposes of maintenance, repair, replacement or 
cleaning of vehicle components that are arranged underneath the operator's 
platform. Since pivoting or removal of operator's platforms usually 
requires cranes or block and tackle arrangements, such operations must be 
performed in shop areas or in locations that are equipped with such 
arrangements. Frequently, disassembly of further components is necessary 
in order to permit pivoting in the first place. The design shown in EP-A-0 
422 489, for example, requires the dismounting of a rear wheel in order to 
permit pivoting sideways of the operator's platform. 
DE-OS-30 07 074 shows an agricultural and/or construction utility vehicle 
with a power lift equipped with two lower guide arms and a cab that can be 
disassembled if not used and deposited in a storage location. For the 
disassembly the cab can be pivoted by means of a push rod about a pivot 
axis located at the rear end of the tractor. On the one hand, the push rod 
is connected in a joint to the lift arm in the lowest position of the 
power lift and on the other hand rigidly attached to a pivot lever rigidly 
connected to the operator's cab. When the lift arm is raised into is 
highest position the operator's cab is pivoted only so far that its center 
of gravity remains ahead of the pivot axis. In this intermediate position 
the operator's cab can be brought manually into a storage position in an 
appropriate storage location. In this arrangement there is no provision 
for retaining the cab in a pivoted position. This has the disadvantage 
that the cab must always be removed as a complete unit and deposited at an 
appropriate storage location. The operator's platform itself with the 
operating components and operator's seat remain on the tractor. This is 
not an absolute requirement for the performance of maintenance and repair 
operations. 
It is also known to provide trucks with operator's platforms or cabs which 
are pivotal towards the front about a horizontal pivot axis. Such designs 
are usually not applicable to agricultural or industrial vehicles because 
their operator's platform are arranged in the rear region of the vehicle, 
and because components such as fenders might interfere with the pivoting 
process. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a utility vehicle with a 
simple system for pivoting the operator's platform to facilitate 
maintenance and repair and installation while avoiding the noted 
disadvantages and problems. 
A further object is to provide a pivot assembly which consists of a few 
components that can be manufactured at low cost and that can be installed 
easily. 
A further object is to provide a pivot assembly which enables a free 
pivoting of the operator's platform without any vehicle components 
hindering the pivoting process. 
These and other objects are achieved by the present invention, wherein a 
utility vehicle includes a vehicle body, an operator's platform and a 
pivot assembly for pivoting the operator's platform on the vehicle about 
an essentially horizontal pivot axis in order to gain access to vehicle 
components located underneath the operator's platform for purposes of 
maintenance or repair operations. The pivot assembly includes at least two 
guide arms of differing lengths and/or oriented in differing, nonparallel 
directions. Each arm having one end coupled at a joint to the operator's 
platform and having another end coupled at a joint to the vehicle body. 
The joints have axes which are generally oriented parallel to each other 
and are spaced apart from one another. It should be understood that the 
arms could be coupled to directly to the vehicle body and/or the 
operator's platform or indirectly through other components attached 
thereto. 
This pivot assembly makes possible a simple and rapid pivoting of the 
operators platform or the operator's cab, without dismount further 
components of the vehicle such as, for example, a rear wheel. Since no 
cranes or block and tackle arrangements are required, the pivoting need 
not be performed in a shop, but may be performed, if desired, at any 
location, for example, in the field. The cab can be secured in its pivoted 
position. This assures sufficient access to vehicle components arranged 
underneath the operator's platform. The pivoting angle made possible by 
the arrangement and the height of pivoting permit all vehicle systems to 
remain connected and operable. For example, lines for the air conditioning 
system, the heating system, the steering, the brakes, the hydraulic 
components and further electrical and hydraulic lines can be designed and 
routed in such a way that they need not be separated for the pivoting. The 
lines can be routed in the rear region of the vehicle and be provided with 
sufficient flexibility that they make possible pivoting over the full 
pivoting angle. 
The two guide arms interact as a four-bar linkage so that the operator's 
platform pivots and moves linearly. By establishing the lengths, direction 
and position of the axes of the connecting joints of the guide arms, the 
pivoting path and the possible range of the pivot angle of the operator's 
platform can be varied within wide limits and made to conform to the 
available space. The pivoting movement assures that, during the entire 
pivoting process, an adequate distance is maintained between the 
operator's platform and the components of the utility vehicle. This is 
particularly advantageous if fenders for rear tires of the utility vehicle 
are fastened to the operator's platform. The invention assures that, 
during the pivoting of the operator's platform, the fenders do not collide 
with the tires, so that pivoting is possible without dismounting of the 
tires. The pivoting movement of the operator's platform can be described 
as a pivoting about an imaginary center of rotation whose position changes 
continuously during the pivoting process and that represents an 
intersection of imaginary extensions of the guide arms. If the pivoting 
angle is limited by the lengths of. the guide arms and the locations of 
the joints of the guide arms in such a way that the center of gravity of 
the operator's platform does not move to the outside beyond the pivot 
axis, then single-acting hydraulic cylinders can also be used since the 
weight of the operator's platform brings it again into its initial 
position. 
Since the pivot assembly as such consists of few and simple components, it 
can be manufactured easily and at low cost. A simple assembly and 
disassembly of the pivot assembly to the utility vehicle and the 
operator's platform is possible, since for this purpose only the two guide 
arms need to be connected to the vehicle body or the operator's platform. 
Instead of connecting the guide arms directly to the vehicle body or the 
operator's platform, they may be connected through further components 
fastened to the vehicle body or the operator's platform. 
A power motor arranged between two elements of the four-bar linkage 
(vehicle body, guide arm, operator's platform) helps to pivot the heavy 
operator's platforms. Such a power motor may be used exclusively for 
driving the pivot assembly. However, it is particularly advantageous to 
utilize a power motor for the pivoting which is already used for other 
purposes and attached to the utility vehicle. The power motor may, for 
example, be a linear drive such as a hydraulic motor, a spindle drive or 
an electric motor or the like. 
Preferably the power motor is a hydraulic motor, and the necessary 
hydraulic pressure may be supplied by a hydraulic pump which is already 
available on the vehicle for supply hydraulic pressure to other systems, 
such as steering, hydraulic brakes or similar units. The hydraulic motor 
may also be supplied by a separate pressure source independent of the 
vehicle, such as, a manually-operated pump, a hydraulic pressure reservoir 
or an electrically driven external hydraulic pump. In this case the 
vehicle's existing hydraulic pressure source need not be used to pivot the 
operator's platform, and the operator's platform may be pivoted even when 
the vehicle pressure source is not operating. 
The hydraulic motor may be a single-acting or a double-acting piston and 
cylinder unit. With an external pressure supply of a single-acting 
hydraulic motor, the lowering of the operator's platform occurs when the 
connection between the pressure source and the hydraulic motor is 
interrupted. Preferably, the hydraulic fluid would be released via a 
throttle, so that a uniform and not too rapid lowering of the operator's 
platform can be achieved. 
Preferably, a single pin can be used to couple the power motor, the first 
guide arm and the operator's platform to each other. Utility vehicles are 
frequently provided with a hitch to which implements or loads can be 
attached. A typical hitch includes two hydraulically actuated lift arms 
which are pivotally coupled to the vehicle body and which can be raised 
and lowered by associated lower guide arms. Such a lift arm can be coupled 
to the operator's platform or to a component attached to the operator's 
platform. By using the lift arm as the first guide arm of the pivot 
assembly, another existing component can be utilized for a second function 
so that the number of components is reduced. The lift arm may be pivoted 
by a single-acting piston and cylinder device that actuates two hitch lift 
arms through a lift shaft. 
A lift link is coupled between a free end of the lift arm and the lower 
draft links of the hitch. The threepoint hitch also includes upper links 
coupled to the vehicle body (for example, see ISO 730-1). The connecting 
joint between the lift arm and the operator's platform is located in a 
central region of the lift arm, while the lifting rod or lifting spindle 
engages a free end of the lift arm. Preferably, the hitch lift cylinder is 
utilized as the power motor, and it can also be coupled to the central 
region of the lift arm of the hitch, so that a common pin connects the 
lift cylinder, the operator's platform and the lift arm to each other. 
Since in known hitches, the lift arm and the lift cylinder are coupled by 
pins, an elongated pin can be used to accommodate the lift assembly. In 
order to move the horizontal pivot axis into the farthest possible rear 
region of the vehicle or even into a region outside of the vehicle, it is 
advantageous to fasten a horizontally extending strut to the operator's 
platform. A first guide arm can be coupled to a central region of the 
strut and a second guide arm can be coupled to the free end of the strut. 
This design permits good access to components located underneath the 
operator's platform with a relatively small pivot angle. Preferred pivot 
angles lie between 20 and 55. Small pivot angles are frequently sufficient 
for purposes of maintenance or for the replacement of small units, so that 
a complete pivoting of the operator's platform is necessary only for 
larger repairs or for extensive maintenance operations. 
The struts may be rods which can be inserted very simply into corresponding 
openings in a frame of the operator's platform and fastened thereto, thus 
avoiding costly connecting and fastening devices. 
In view of the heavy weight of the operator's platform a pivot assembly is 
preferably provided on each side of the utility vehicle. The corresponding 
axes of the connecting joints of the guide arms are aligned with each 
other. In this case, the lift arms of the known hitch can be utilized, 
since they are supported in bearings on a common lifting shaft, free to 
pivot. A hydraulic motor is coupled to a central region of each lift arm, 
and the hydraulic motors are supplied with hydraulic pressure by a common 
pressure source. 
The pivot assembly includes at least one strut and one guide arm. The strut 
is connected to the guide arm, free to rotate, and can be connected 
rigidly to the operator's platform. The strut is coupled to a power motor 
and to a further guide arm which can be pivotally connected to the vehicle 
body. Such a pivot assembly may be attached permanently to the vehicle. 
However, it is particularly advantageous if the pivot assembly can be 
attached simply and rapidly to the utility vehicle and then disassembled 
similarly after the completion of maintenance and repair operations, so 
that the pivot assembly does not hinder the normal operation of the 
vehicle and so that it cannot be damaged in rough operating conditions. 
The position of the connecting joints of the pivot assembly can be varied 
so as conform to various vehicle or model types that have varying 
dimensions. The connecting points can be provided by movable or 
interchangeable retainers or other removable components attached to the 
strut or the guide arms. 
If the power motor and the further guide arm are components of a hitch, the 
number of components of the pivot assembly that must be attached to or 
disassembled from the pivot assembly is reduced further. The one guide arm 
can be connected to the free end of the strut, free to rotate. The power 
motor and the further guide arm are coupled to a central region of the 
strut in order to improve the pivot axis of the operator's platform. 
The invention can also be applied to agricultural and non-agricultural 
tractors, other agricultural vehicles, such as combines, forage harvesters 
and other harvesting machines, and to industrial vehicles such as loaders, 
dredges or cranes.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows an agricultural tractor 10 with a frame 12 in which an engine 
and gearbox 14 and various other vehicle components (not shown) are 
mounted. A front axle 16 and a rear axle 18 are fastened to the frame 12. 
In the region of the rear axle 18 an operator's platform 20 in the form of 
a cab is mounted on the frame 12. Fenders 24 are fastened on both sides of 
the vehicle 10 to the operator's platform 20. 
An implement hitch 28 is mounted at the rear side 26 of the vehicle 10 
(with respect to its direction of operation). Since the hitch 28 is 
symmetrical about a longitudinal centerline of the vehicle 10, only its 
components on the right side will be described in detail in the following. 
The hitch 28 includes a first guide arm or lift arm 30 which is coupled to 
lift shaft 32. The lift shaft 32 is rotatably supported or mounted in the 
vehicle body 36 by bearings (not shown), so that the lift arm 30 is 
pivotally coupled to the vehicle body. At a central region of the lift arm 
30 a side leg 31 is provided, to which a power motor 34, in the form of a 
single-acting piston and cylinder arrangement, is connected at a joint 
formed by a pin connection. The other end of the power motor 34 is 
connected in a joint to a differential housing, that is part of the 
vehicle body 36 of the utility vehicle 10. The lower guide arms 35 and the 
lifting rods 37 of the hitch are configured in conventional manner. For 
the sake of clarity the upper guide arm is not shown in the drawing in any 
further detail. As shown in FIG. 2, the lift arm 30 moves from an initial 
lower position 38 over several intermediate positions to an upper end 
position 40 when the hydraulic motor 34 is extended. 
The operators platform 20 includes a four-sided frame. The two lower 
elements 21 at the sides of the frame that extend in the longitudinal 
direction of the vehicle have slots 23 which are open to the rear. A strut 
52 configured as a profiled rod is inserted into each of these slots 23. 
The outer shape of the strut conforms to the shape of the slots 23. If 
necessary the struts 52 can be fastened in a simple manner to the frame 
for easy assembly or disassembly. To secure the struts 52 to the frame 
conventional pin connections can be used (not shown). 
A link 42 is pivotally coupled to a free end of each strut 52 at a joint 
56. The joint may be configured as a pin connection that can be easily 
connected and disconnected, in which the strut 52 and the link 42 are each 
provided with an associated bore through which a pin is inserted that is 
secured by appropriate retaining elements. The other end of the link 42 is 
connected in a joint to the differential housing 36. For this joint a pin 
connection may also be provided, in which a pin can be fastened to the 
differential housing 36 which is inserted through a bore in the link 42 
and makes possible a simple assembly and disassembly of the link 42. The 
pin used here is preferably the same pin that usually forms the joint 
between the hydraulic motor 34 and the differential housing 36. If 
necessary, the pin used here previously may have to be replaced by a 
longer pin, so that the link 42 can be added to the assembly. 
The central region of the strut 52 is connected through a joint 54 with a 
side leg 31 which projects downwardly from the lift arm 30. For this 
purpose the strut 52 is provided with a bore which receives a pin. This 
pin is the same pin that couples the lift arm 30 with the hydraulic motor 
34. In contrast to previous commonly used pins, the pin used here is an 
extended length pin, which extends through the bore of the strut 52. 
Appropriate rapid release retaining elements (not shown) may be used to 
secure the pin to the strut 52. 
As long as the two struts 52 and the two links 42 are not permanently 
fastened to the vehicle 10, then the vehicle 10 does not differ to a 
notable degree from a conventional tractor with hitch. For the pivoting of 
the operator's platform 20, the struts 52 and the links 42 are fastened to 
the vehicle in the manner shown and described. Furthermore, attaching 
elements, that secure the operator's platform 20 to the vehicle body 36 
are released. If the power motors 34 are supplied with pressurized 
hydraulic fluid and are extended, the forward part of the operator's 
platform 20 is raised from the vehicle body 36, permitting access to 
vehicle components located underneath the operator's platform 20. 
The struts 52, the links 42 and an electric or manually operated external 
hydraulic pump can be assembled and held as separate unit, so that it can 
be fastened to the vehicle if necessary in order to pivot the operator's 
platform 20. For the hydraulic drive of the hydraulic pump a "T" fitting 
(not shown) may be provided in the hydraulic circuit of the power motors 
34, the central connection of the "T" is connected over a shut-off valve 
with a hydraulic coupling (not shown). 
It should be emphasized that it may be necessary to release or disconnect 
the electric and hydraulic connecting lines and mechanical linkages 
extending between the operator's platform 20 and the vehicle body 36 
before the pivoting operation. There is a particular advantage, however, 
in designing and arranging the brake lines, the steering lines, the heater 
lines, the lines of an air conditioning system and further electrical and 
hydraulic lines as well as any necessary connecting linkages (not shown) 
in such a way that they do not have to be opened for a pivoting operation. 
For this purpose portions of the lines, in particular, those in the rear 
region of the operator's platform 20 are routed transverse to the 
direction of operation. Aside from the saving in maintenance time, the 
ability to keep the lines connected has the advantage that the prime mover 
can continue to operate with the operator's platform 20 pivoted. Thus, a 
hydraulic pump can also be driven so as to supply the power motors 34 with 
hydraulic fluid. The lift arm 30 of the attaching arrangement 28 forms a 
pivot assembly 44 together with a second guide arm or link 42, by means of 
which the operator's platform 20 can be brought from its initial position 
in contact with the vehicle 10 (the solid lines in FIG. 2) over 
intermediate positions (shown with dashed lines) into a pivoted end 
position 48. In order to pivot the operator's platform 20 the power motor 
34 must be extended. Thereby the lift arm 30 moves along the dashed line 
60 into its upper end position 40. The operator's platform 20 connected to 
it in a joint is thereby also raised. Since the operator's platform 20 is 
connected in a joint to the vehicle body 36 through the link 42 with 
constant length, the operator's platform 20 performs a pivoting movement 
about an imaginary pivot axis. The position of this pivot axis is a result 
of the geometry of the individual components of the pivot assembly 44, 
that is, the location of the connecting joints and the lengths of the lift 
arm 30, the link 42 and the strut 52. 
In addition to the initial position and the final pivoted end position 48 
of the operator's platform 20 in FIG. 2, several intermediate positions 39 
are shown in dashed lines. During pivoting the lift arms 30 and the links 
42 pivot about each of their connecting joints at the vehicle body 36. 
During pivoting the connecting joint 54 between the strut 52 and the lift 
arm 30 moves in a circular path 64, whose center form the axis of the 
lifting shaft 32. The connecting joint 56 between the strut 52 and the 
link 42 moves in a circular path 66 whose center forms the connecting 
joint of the link 42 on the vehicle body 36. Since the distance between 
the two aforementioned connecting joints 54, 56 remains constant, the 
result is that the operator's platform 20 both translates (at an angle 
upward and to the rear) and pivots, so that the rear point of the frame of 
the operator's platform 20 moves along the curve 62. Preferably, two 
essentially identical pivot assemblies are provided, and they have 
corresponding connecting joint axes which are aligned with each other. 
While the present invention has been described in conjunction with a 
specific embodiment, it is understood that many alternatives, 
modifications and variations will be apparent to those skilled in the art 
in light of the foregoing description. Accordingly, this invention is 
intended to embrace all such alternatives, modifications and variations 
which fall within the spirit and scope of the appended claims.