Cover plate for access opening

A cover plate is provided for an access opening in a plate structure that forms part of a housing. The cover plate has a rod at one end thereof that has opposite ends bent toward the plate structure and engaging the internal surface of the plate structure. The plate structure also has lips thereon that engage the internal surface of the plate cover and limit movement of the plate structure to a position in which its edges are co-extensive with the edges of the opening. A further means is provided between the plate structure having the opening and the cover plate which draws the cover plate into engagement with the stops or lips while, at the same time, distorting or stressing the rod as the rod end of the cover is forced into the closed position. By placing such stress on the rod, the entire plate cover is held firmly against the lips and is prevented from rattling or becoming loose.

BACKGROUND OF THE INVENTION 
In large land-working vehicles in which there is provided expensive and 
complicated hydraulic and/or electronic devices, there is commonly 
provided a housing structure which covers such devices. Due to the nature 
of the activity of the earth-moving piece of equipment, this housing 
structure often is of a thick steel plating which can withstand jagged and 
rugged terrain. Provided in the plate structure forming the housing are 
access openings so that an operator or a mechanic can work on the more 
complicated devices covered by the housing. Commonly, the cover plate is a 
very thick metal plate and may, in some instances, be bolted in its closed 
position by suitable structure provided on the housing. One problem that 
exists with such cover plates is that in many instances, it is necessary 
to work from under the vehicle for removing the plate. It is often 
difficult to judge the amount the bolts have been loosened. In some 
instances, the cover plate will break loose and can fall on the person 
under the vehicle, causing injury to him. 
Another common method of mounting a cover plate is to provide a hinge along 
the edge of the cover plate and bolts to hold the cover plate in a closed 
position. However, one of the problems that exists with such a mounting 
arrangement is that often, the hinge pin or the hinges carried by the 
cover plate or plate structure become worn and cause rattles or other 
noise to occur at the location of the cover plate. Also, as the cover 
plate becomes loose, due to the hinge, it will lead into other problems, 
such as permitting dirt and foreign matter to enter into the small cracks 
or breaks in the housing around the cover plate. Also, hinge assemblies 
are often difficult to remove or disassemble when it is desired to 
completely remove the cover plate. 
DESCRIPTION OF THE PRESENT INVENTION 
With the above in mind, it is a primary object of the present invention to 
provide a cover plate for an access opening in a housing and to provide 
simple structure for mounting the cover and for holding it in a tight, 
noiseless closed position. The access opening in the housing is shaped to 
have a main part and an extension part to one side of the main part. The 
cover plate is of the size and shape to fit into the opening and the 
portion of the cover plate that fits into the extension part of the 
opening carries on its internal surface a rod element which extends beyond 
the edges of the cover plate and engages the internal surface of the plate 
structure forming part of the housing. Also provided on the internal 
surface of the plate structure are small lips or stop elements that engage 
the internal surface of the cover plate and limit movement of the cover 
plate to that in which the internal and external surfaces of the cover 
plate and plate structure are substantially co-planar. The rod element 
serves as a hinge. The end sections of the rods are bent toward the 
internal surfaces of the plate structure. Provided on the opposite side of 
the plate structure is a bolt, or other means, which can draw the cover 
plate against the stop elements while at the same time, distorting the rod 
end sections as that end of the cover plate is forced into position 
against the stops. Through the distortion of the rod end sections, there 
is created a biasing force causing the cover plate to be held firmly in 
position. Thus, there is eliminated the rattling and noise that would 
otherwise occur, as well as making a comparatively tight fit between the 
cover plate and the edges of the opening in the plate structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, there is provided a large crawler tractor 10 
having a loader device 11 at its forward end which is controlled from an 
operator's station 12. For such a tractor, there is normally provided a 
hydraulic drive, not shown, which is contained in a large housing 
structure 13 at the rear center portion of the tractor. Since the tractor 
normally operates in areas where stones, jagged rocks, and foreign matter 
may extend up through the ground, the housing structure 13 is made up of 
rather thick metal plating which will withstand abuse from such material. 
On the underside of the housing structure, there is provided a plate 
structure 14 which may have several access openings, one of which is shown 
at 15, under the transmission, engine, or hydraulic controls. In the 
particular instance shown, the plate structure 14 is on the lower rear 
portion of the housing and the access opening permits entry from 
underneath the tractor into the hydraulic mechanism for the tractor. It 
should, however, be understood that the cover plate, and its method of 
mounting and moving in and out of position, as presently described, may be 
used on numerous devices and in different locations. The plate structure 
14 extends outwardly from edges 16, 17 that define opposite sides of the 
opening 15 and from edges 18, 19 which define the ends of the opening. As 
clearly shown in FIG. 2, the edges 16, 17 and 18, 19 are parallel to one 
another. The edges 16, 17 extend, in length, a major portion of the 
opening to a reduced or smaller end extension of the opening adjacent the 
end 19, such being defined by longitudinal, parallel edges 20, 21 that are 
inwardly with respect to the edges 16, 17. 
Referring now to FIG. 3, the cover plate 25 has parallel and longitudinally 
extending edges 26, 27 and end edges 28, 29. A reduced end portion, 
defined by edges 30, 31, which are also parallel to one another, extends 
from the end edge 29 and joins with the edges 26, 27 at junctures a short 
distance from the edge 29. As can best be seen from viewing FIGS. 2, 3, 
and 4, the cover plate 25 fits into and has the same shape as the opening 
15. Thus, the cover plate has an enlarged portion between the edges 26, 27 
that closes the main part of the opening 15 and a small portion between 
the edges 30, 31 that closes the matching part of the opening 15 between 
the edges 20, 21. 
When in place, as shown in FIG. 6, the cover plate 25 has internal and 
external surfaces 32, 33 that are co-planar or co-extensive with the 
internal and external surfaces 34, 35 of the plate structure 14 forming 
part of the housing. Welded to the internal surface 34 is a series of stop 
plates or elements 36 that extend into the opening 15 and serve to limit 
the movement of the cover plate to a position in which the internal 
surface 32 of the cover plate is co-extensive or co-planar with the 
surface 34 of the plate structure. Two of the stop elements 36' are on 
opposite sides of the opening 15 and in the area where the respective 
edges 20, 21 join with the edges 16, 17. Reviewing FIG. 4, it should also 
be noted that the stop elements 36, 36' extend into the opening 15 about 
the same distance as the edges 20, 21 are inboard of the edges 16, 17, 
respectively. 
Referring now to FIG. 5, a hinge rod 37 extends across the small end 
portion of the cover plate 25. It is welded at 40 to the internal surface 
32 at the central portion of the rod 37. The rod 37 has opposite end 
sections 38, 39 that project outwardly from the central welded portion. 
The extreme end portions of the end sections 38, 39 are bent or turned 
toward the outer side 33 of the cover plate 25 and extend out of the plane 
of the surface 32. 
At the end of the opening 15, defined by the edge 18, there is provided a 
latch plate 41, welded at 42 to the internal surface 34 of the plate 
structure 14, extending into the opening 15. The latch plate 41 has a 
threaded opening 43 that receives the end of a bolt 44. The latch plate 41 
may also serve as a stop at the end of the opening 15 that engages the 
interior surface of the cover plate 25. The bolt 44 is carried in a 
recessed opening 45 formed in the outer surface 33 of the cover plate, 
such being necessary in order to prevent the head of the bolt 44 from 
being harmed by contacting jagged stones or other material that can be 
found where industrial loaders are used. 
Assuming the cover 25 is completely removed from the access opening 15, it 
can be replaced by inserting the small end of the cover and the rod 37 
through the large portion of the access opening and turning it to its 
correct attitude. The small end of the cover plate may be moved between 
the stop elements 36, 36' until the rod end is in the small end of the 
opening 15. The rod 37 may then rest upon the internal surface 34 of the 
plate 14. The rod is used as a hinge rod and the plate raised into a 
position in which the bolt 44 may be started into the threaded opening 43. 
By tightening the bolt 44, the cover plate 25 is moved into a position of 
contact with the stops 36, 36'. As this occurs, the rod 37, and 
particularly the end sections 38, 39, will be bent from their free state, 
as shown in FIG. 5, into their deformed state, as shown in FIG. 6. The rod 
37 then operates as a spring to tightly hold the small end of the cover 
plate 25 on the plate 14. This will, of course, prevent any rattling or 
loosening of the cover plate 25 at that end. The bolt 44 will hold the 
opposite end tightly against the latch plate 41 and the stops 36, 36'. The 
stops 36, 36' serve as lips that contact the upper surface 32 of the cover 
plate. 
When it is desired to remove the cover plate 25, the bolt 44 is removed and 
the cover plate 25 is permitted to swing downwardly using the rod 37 as a 
hinge pin. The cover plate then may be turned 90 degrees and completely 
removed from the access opening 25. It should also be understood that the 
two stop elements 36' will prevent the rod from accidentally moving into 
the large portion of the access opening 15 and consequently, the cover 
plate 25 is prevented from accidentally twisting or turning unless the 
operator actually lifts the rod 37 over the stop element 36'.