Door positioner

An operator's station mounted on the rear bogie of an articulated tractor and having a door that swings out from a hinge on its rear edge and in which the front bogie may swing relative to the rear bogie so that parts of the tractor on the front bogie may move into the zone of swinging of the door, the improvement residing in the hinge structure and door positioning structure which automatically shifts the door into either its fully opened or fully closed positions and out of the area in which the aforesaid tractor parts may shift. The structure includes means for hinging the door to swing about a vertical axis from its rear edge and a link structure that is connected to a post on the operator's station and which has a rear end connected thereto on a pivot structure that is offset inwardly and rearwardly from the hinge axis of the door. The link structure further includes a portion that extends from its rear and forwardly alongside a face of the door to a front end which is connected to the door. The link structure also includes a spring under tension which creates a biasing force on the door to swing the door to its fully opened and closed positions as the link structure passes to opposite sides of the hinge axis of the door.

BACKGROUND OF THE INVENTION 
On articulated tractors, there is provided an operator's station or 
compartment on one of the bogies with a side door permitting egress from 
and ingress into the compartment. Often, this door will be left slightly 
opened and as the front bogie swings toward the rear bogie when the 
tractor is turning, portions or parts on the front bogie will strike the 
door, either damaging it or destroying it in its entirety. Damage to the 
door will, of course, prevent it from closing properly. This could create 
problems with respect to the heating, air conditioning, or sound system 
within the operator's station. Striking of the door by the tractor parts 
can destroy the glass window which is normally heat-treated and rather 
expensive to replace. Therefore, while carelessness by the operator may be 
the cause of damage to the door, there nevertheless often occurs a 
situation where the door is left only partially opened and damage occurs 
to the door. 
SUMMARY OF THE INVENTION 
With the above in mind, it is proposed to provide a hinge structure between 
the rear portion of the door and a post that is part of the operator's 
compartment which causes the door to swing from a fully opened to a fully 
closed position. 
A retractible and extendable link structure is provided and has one of its 
ends connected to a vertical pivot on the operator's station that is 
offset inwardly and rearwardly from the hinge axis of the door. The link 
structure extends from that end alongside a face of the door and has its 
opposite end connected to the door. The hinge is positioned vertically 
with respect to the link structure so that the entire link structure may 
swing through an extension of the hinge axis and to opposite sides of the 
axis. A part of the link structure includes a pre-stretched spring which 
biases the door to move on its hinge axis to its fully opened and fully 
closed positions.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In an articulated tractor 10, having a front bogie 12 and a rear bogie 14, 
the front bogie 12 has a front frame 16 that is connected at its rear end 
to a rear frame 18 so that the two frames 16 and 18 swing relative to one 
another about a vertical axis, the location of which is indicated at 20. 
The front bogie 12 includes a loader 22 having lift arms 24, 26 pivotally 
mounted on posts 28, 30. The front frame 16 is supported on left- and 
right-hand wheels 32, 34. The rear bogie 14 is carried on left- and 
right-hand support whels 36, 38 and has at its rear end the power unit or 
engine, indicated in its location by the engine cowling 40. Just forward 
of the engine 40 is an operator's compartment 42 that includes a side door 
44 that is hinged at its rear edge on a vertical post 46 so that it can 
swing between a fully opened position and a fully closed position, as 
shown in FIG. 2. The compartment 42 further includes the operating 
controls for the entire tractor with a seat, steering wheel and loader 
controls carried within the compartment. 
The front frame 16 is swung about its pivot axis 20 by power means that 
includes hydraulic cylinders such as are shown at 48. Referring to FIG. 2, 
the path of the forward free edge of the door is shown by the circular 
representation at 50. It will further be noted that as the cylinder 48 on 
the right side of the respective frames 16, 18 is extended, the left post 
28 and a wheel fender 52 will swing into the zone or arc 50 of the door 
44. Therefore, if the door 44 were left in a position of being only 
partially opened, the fender 52 or post 28 would contact the free edge and 
crush the door. It should also be noted that no interference between the 
door 44 and the fender or other parts of the front tractor bogie occurs 
when the door 44 is in it fully opened or fully closed position. It is the 
purpose of the present invention to provide structure, presently to be 
described, which will automatically move the door 44 to its fully closed 
position or its fully opened position, but will not retain it in any 
intermediate position between these limits. 
Referring now to FIGS. 3-4, there is provided on the outboard side of the 
upright post 46 bracket supports, one of which is shown at 54. The bracket 
support 54 is welded to the outer surface of the post 46 and carries 
adjacent its outermost end a hinge pin or rod 56. The hinge pin 56 is 
fixed against axial shifting by a set screw 57. While FIGS. 3 and 4 show 
only one hinge suport, it should be understood that there is a second or 
upper hinge support identical to that of 54 which carries the upper end of 
the hinge pin 56. Mounted on the hinge pin is a hinged journal 58 which 
has welded to its outer surface and "L" shaped hinge bracket 60 that has 
one leg projecting fowardly and welded to the rear edge of door 44. Again, 
it should be understood that a similar hinged journal 58 and bracket 60 is 
provided adjacent an upper hinge support 54 and stabilizes the door on the 
respective hinge brackets 60 and their respective journals 58. Thus, the 
door 44 may swing between its fully opened and fully closed positions on 
the hinge pin 56 and about the upright axis of the pin. 
Mounted on the rear vertical face 62 of the hinge support 54 is a link 
support 64 that has an opening forming a vertical pivot therein. A link 
structure, indicated in its entirety by the reference numeral 68, extends 
from the pivot opening forwardly along the outer face of the door 44. The 
link structure 68 includes an "L" shaped rod 70 that has a vertical leg 72 
extending through a pivot opening of the link support 64. In viewing FIGS. 
3 and 4, it will be noted that the axis of the pivot opening of the 
support 64 and the leg 72 is rearwardly and inwardly with respect to the 
axis of the hinge pin 56. A pair of locking rings is positioned on the 
tractor provided above and below the bracket 64 for purposes of holding 
the vertical leg portion 72 in the bracket support 64. The link 70 is 
therefore capable of swinging about the vertical axis of the pivot 
opening. The hinge pin 56 terminates above the link structure 68 and 
particularly the link member 70. The forward end of the link member 70 is 
flattened at 74 and has an opening 76 therein for receiving the rear end 
of a pre-stretched spring 78, the forward end of which extends through an 
eyelit bolt 80. The eyelit bolt has its threaded free end extending 
through a bracket 82 welded to the outer surface of door 44. A nut 84 is 
provided for adjusting the tension in the spring 78. A U-shaped cover 86 
is provided on the outer surface of the door 44 and covers the spring 78, 
the forward end of rod 70, and the rear connection between the spring 78 
and the bracket. 
Reviewing FIGS. 3 and 4 for understanding the operation of the door and its 
mounting structure, it will be noted that the force of the spring 78 is 
directed along the axis of the entire linkage 68 and through the axis of 
the vertical leg portion 72. The line of force, as indicated in FIG. 3 at 
88, will swing with the door 44. Thus, as an operator would open the door 
44 from the position shown in full in FIG. 3, the line of force 88 will 
move in a clockwise direction and always through the axis of the pin 
portion 72 and its opening. The spring 78, being in a pre-stretched 
position, will resist outward movement of the door 44 and should the door 
44 be released, the spring would cause the door to move back to its fully 
closed position. However, as the door swings to the opposite side of the 
axis of the rod 56, the line of force will pass to the left or to an 
overcenter position and the force 88 will thereafter cause the door to 
swing toward a fully opened position and to be retained in that opened 
position. Thus, for release of the door in any position between its fully 
opened and fully closed position, the door structure will automatically 
shift either to the fully opened or fully closed position, depending at 
where the door is released.