Seat and control lever interlock

A seat and hydraulic control lever interlock for lift trucks in which access to a battery compartment is in part enabled by pivoting the operator seat forwardly over the steering wheel, which pivotal movement causes interlocking lever means between the seat pivot and hydraulic control levers to actuate to an armed position. Forward pivotal movement of the control levers to an inoperative position to clear the battery compartment allows the lever means to move to a position in which the control levers are held in such inoperative position until the seat is pivoted rearwardly over the battery compartment.

BACKGROUND OF THE INVENTION 
The field of art to which the invention pertains relates to industrial 
trucks, and more particularly to operator seat and control lever assembly 
for use on such vehicles. 
Full and open access to the power source compartment of sit-down rider lift 
trucks for servicing and in particular replacement of power source 
batteries in electric trucks is an important part of the design of such 
lift trucks. Such components as the cover hood, hydraulic control levers 
and seat have been heretofore mounted for pivotal movement outside of the 
vertical cube of the source battery, for example, in such devices as are 
disclosed in co-pending U.S. applications Ser. No. 136,013, filed Mar. 31, 
1980 now U.S. Pat. No. 4,312,418, and Ser. No. 209,748 filed Nov. 24, 1980 
now U.S. Pat. No. 4,359,121, common assignee, and in U.S. Pat. Nos. 
2,605,008, 3,610,359 and 4,076,302. Movement of the hood, seat and control 
valve bank to non-interfering positions is disclosed in the first named 
patent application, movement of the seat and hood to non-interfering 
positions is disclosed in the second named patent application, movement of 
valve control means to non-interfering positions in pedestrian and 
stand-up rider battery power lift trucks is disclosed in U.S. Pat. Nos. 
2,605,008 and 3,610,359, and pivotal movement of the seat and overhead 
guard is shown in U.S. Pat. No. 4,076,302. 
In none of such devices and combinations is the problem addressed of 
positively locking out of operative position lift truck control levers 
upon the pivotal actuation in a forward direction of the seat and control 
levers. 
SUMMARY 
The invention relates to a seat and hydraulic control lever interlock for 
lift trucks and the like in which access to a battery compartment is in 
part enabled by pivoting the operator seat forwardly over the steering 
wheel and by pivoting forwardly outside the vertical cube of the battery 
compartment hydraulic control levers. The seat movement actuates 
interlocking levers which maintains the forwardly pivoted inoperative 
position of the hydraulic control levers so long as the seat remains in 
such forwardly pivoted position, return to normal position of the seat 
enabling the control levers to be returned to operative position. 
It is a principal object of the invention to provide in such lift trucks a 
positively maintained forward pivoted position of the control levers 
coordinated with a forward seat position so as to avoid interference with 
battery removal and to prevent movement of the control levers to operative 
positions.

DESCRIPTION OF PREFERRED EMBODIMENT 
A partial view of an industrial lift truck is illustrated at numeral 10 
having a power source battery compartment 12 mounted on a frame 14 having 
pairs of steering and driving wheels 16 and 18, respectively, a 
counterweight 20, an overhead guard 22, a battery cover 24 shown in an 
upright position to expose the battery compartment, an operator's seat and 
supporting structure 26 illustrated in a forwardly pivoted position over a 
steering wheel and post 28, a front cowl 30 adapted to support an 
instrument panel, not shown, and a hydraulic valve and valve lever 
assembly 32, the lever assembly being illustrated in a forwardly pivoted 
and inoperative position. The upright or mast structure of the truck is 
not shown and certain of the above described components are located in 
positions which enables a power source battery in compartment 12 to be 
readily deposited therein or removed therefrom. 
The seat support plate 26 normally extends upwardly and over a portion of 
the battery compartment (FIG. 2) and is secured at its lower edge, as by 
welding, to a support shaft 34 which is supported for rotation from a 
front body plate 36 by a pair of brackets 38, a torsion spring 40 being 
mounted on the one end of shaft 34 and having an upwardly extending spring 
leg member 42 which bears against the inside surface of the seat plate 26 
and continuously urges it in a forwardly pivoted direction. When the seat 
is unoccupied it is tilted by spring 42 to a relatively small formed tilt 
position in which the truck operating systems, not shown, are rendered 
inoperative and the parking brake of the truck is engaged. An operator's 
manual device 44 is mounted from the seat plate and is adapted to 
disengage a seat latch, not shown, so that the seat may be pivoted fully 
forwardly as shown in FIGS. 1 and 3 for battery removal. A latch 46 is 
adapted to release the steering column for forward pivotal movement 
thereof as in FIG. 3 whereby to further open access to the battery 
compartment when the seat is pivoted forwardly over the steering wheel. 
The seat latch and means for rendering the truck systems inoperative upon 
forward tilting movement of the seat do not comprise a part of this 
invention and so have not been disclosed herein. 
The hydraulic control valve and valve lever assembly 32 controls, for 
example, lift and tilt valves of an upright lift cylinder. It comprises a 
pair of valve levers 52 and 54, and a seat and control lever interlock 
assembly 56, the valve levers being connected to hydraulic valve means 58 
enclosed within an enclosure 60 (FIG. 5) which is mounted from a valve 
lever support plate 61 which in turn is secured to the valve housing 62. 
The valve assembly 62 is secured by bolts, not shown, to body plate 36. 
The valve levers 52 and 54 extend upward through an opening 63 in 
enclosure 60 and are adapted to be actuated to various control positions; 
viz, a rearwardly extending position in which the seat is ordinarily 
occupied for operating the valve assembly 58 shown at 54a, a neutral 
position 54b which corresponds to the FIG. 2 position, and a forwardly 
pivoted position 54c which corresponds to the FIG. 3 position wherein the 
valve lever is held in a forwardly pivoted inoperative position by the 
control lever interlock 56 to be described, in which latter position the 
battery may be removed from or deposited in the battery compartment 
without interference by the valve levers. 
The seat and control lever interlock 56 in its various operating positions 
is best shown in FIGS. 4A, 4B and 4C. With the seat in a normal slightly 
forwardly tilted position, the operator being off of the truck, the parts 
of the interlock assembly are as shown in FIG. 4B. In that position a 
lever 66 which is secured to the one end of pivot shaft 34 is positioned 
to maintain a control rod 68 connected thereto in the position shown which 
extends angularly and upwardly through an opening 70 in the housing 60 
into contact with the one end of an interlock lever 72. The pair of 
slotted valve spools 58 project through support plate 61 for connection 
with complementary slots 78 in the valve levers, the valve levers being 
secured by a pin 80 in openings of spaced upwardly projecting ears 82 of 
the support plate 61, interlock lever 72 being pivotally supported on a 
pin 84 which extends through openings and ears 86 of the plate 61. 
When the seat is in its normally slightly forward tilted position with the 
operator off the seat, as shown in FIGS. 2 and 4B, the control rod 68 is 
actuated to a down position by lever 66 on seat support shaft 34 out of 
contact with arm 90 of interlock lever 72 so that the transverse interlock 
bar 72 falls forwardly of its own weight so as to contact the rear 
surfaces of valve levers 52 and 54 as shown in FIG. 4B. The interlock 
structure is thus "armed" to be actuated in either direction to either 
operate the valve spools from the position of FIG. 4A or lock out the 
valve control as in FIG. 4C wherein lever 72 has fallen into the position 
shown beneath control lever 52C. In other words, as indicated previously, 
for battery removal the steering post is pivoted forwardly, as well as the 
seat assembly and plate 26 to the position of FIGS. 2 and 4B, wherein 
rotation of the seat plate rotates support shaft 34 and lever 66 to 
thereby effect a lowering of control rod 68 as shown permitting the weight 
of interlock 72,90 to rotate it forwardly to a position wherein the 
interlock bar 72 thereof rests against the rear surface of the valve 
levers, or in a partially forward pivoted position. To complete the 
sequence of steps for preparation for battery removal the valve levers are 
rotated fully forwardly, as in FIG. 3, which permits the weight of the 
valve interlock 72,90 to pivot it further forwardly such that bar 72 
pivots to the position of FIG. 4C wherein it is located beneath the rear 
lower surface of each valve lever thereby preventing operation of the 
levers in either direction, in which positions the valve levers are 
inoperative to operate the valves. 
With the hood located in its illustrated vertical position shown in FIG. 1, 
the battery may now be removed from compartment 12, or deposited therein, 
following which a reversal of the sequence of movements of the hood 24, 
seat assembly, steering posts and valve members is effected, rearward 
pivotal movement of the seat assembly again effecting a raising of control 
rod 68 by lever 66 so as to actuate interlock bar 72 by upward movement of 
arm 90 to a non-interfering relation to the valve levers as in FIG. 4A 
thereby permitting subsequent operation thereof in either direction to 
operate the valves. Thus, the hydraulic valve levers which normally extend 
rearwardly over the front portion of the battery compartment may be 
positively maintained in a non-operative position fully forwardly of the 
battery compartment for deposit or removal of the battery without 
accidental actuation of the hydraulic valves associated therewith. 
Although we have described and illustrated a preferred embodiment of our 
invention, it will be understood by those skilled in the art that 
modifications may be made in the structure, form, and relative arrangement 
of parts without necessarily departing from the spirit and scope of the 
invention. Accordingly, it should be understood that we intend to cover by 
the appended claims all such modifications which fall within the scope of 
the invention.