Apparatus for removably connecting an implement to vehicle power arms

A skid loader includes forwardly projecting power arms. A carrier frame is hingedly mounted to the power arms by pivot pins and is adapted to support a working implement. The working implement is connected to the carrier frame by locking pins movably disposed on the carrier frame. The locking pins are actuated by a hydraulic device which is supplied with hydraulic fluid by a fluid passage, a portion of which passes through a pivot pin.

SUMMARY 
The purpose is to improve a lift truck having two power arms for elevating 
and lowering which are energized by an onboard hydraulic system and on the 
forward ends of which arms, an implement frame is hingedly affixed by 
means of pivot pins, and said frame possesses means for the securement of 
said installed implement as well as locking pins for a latch-in, latch-out 
procedure. The improvement lies therein, that a rapid and safe deposition, 
change, or lifting of a load is possible wherein 
a.) each of the locking pins is movable with the help of a pressure 
cylinder, 
b.) each of the locking pins is made movably active by the hydraulic fluid, 
which locking pins receive said hydraulic fluid through an axial boring in 
at least one pivoting pin, and 
c.) by which pivoting pins, the implement frame and the power arms of the 
lift truck are hingedly linked. 
THE AREA OF THE INVENTION 
The invention concerns a lift truck with two, hydraulically actuated power 
arms for lifting and lowering. On the forward ends of said arms, a 
carrying frame is hingedly affixed by means of pivot pins for the 
acceptance of operational implements. The means of securing the installed 
implements are comprised of locking pins which allow engagement or 
disengagement of said implements. 
The lift trucks involved are typified by, for instance, a small pick up and 
transport vehicle, which, on the front end of the power arms shows a 
substantially vertical carrying frame for operational implements, which 
frame is hingedly fastened to said arms by horizontal pivot pins. The 
frame can be pivoted by mechanical connection to a hydraulic cylinder. 
The frame enables the placement thereon of various working implements, 
namely gripping tongs, forks for pallets or refuse material, gravel 
scoops, or the like. These implements are secured by means of locking pins 
inserted in aligned borings in the outer periphery of the carrying frame 
and in corresponding locations of the implement. 
Technological Background 
The hydraulic power arms to lift and lower are extended forward from the 
area behind the cab and are located immediately at each side thereof. This 
gives rise to substantial danger to the driver which forced incisive 
safety procedures. The operator's cab is, at each side, covered with a 
wire netting, a contact switch in the seat, as well as other devices, make 
sure that the lift truck, inclusive of the hydraulic and lift/lower 
mechanism is without motion if the operator rises from his seat. Since the 
locking pins must be inserted and removed by hand, consequently the 
driver, in order to change, remove or install an implement must leave the 
lift truck, manipulate the locking pins, and then again mount into the 
cab. While he is out of the cab, then the hydraulic is shut off by the 
seat switch. This operation is, accordingly, time consuming and because of 
the entry-reentry, is also fraught with danger. 
Thus the purpose of the invention is, to so improve the equipment of the 
conventional type, that a rapid and safe change, removal or installation 
of the implement is possible. 
A BRIEF DESCRIPTION OF THE INVENTION 
The locking pins can be activated by means of the pressure cylinder with 
the fluid of the branched hydraulic system. One pressure cylinder suffices 
for one coupled group when mechanically joined locking pins are used. If 
mechanical joining is not employed, then one pressure cylinder must be put 
in place for each locking pin. From the hydraulic cylinder(s), the 
hydraulic fluid is fed through borings in the implement carrier frame to 
the pivoting pins in the lift-arms. This permits firm transfer connections 
on the outer side. Inside the implement carrying frame, unbalanced 
movements can be equalized by means of tube connectors. Advantageous in 
this case, are rotatable sleeve connections. This gives consideration to 
the rough operation of a lift truck in operation. This way, the required 
hydraulic fittings for the connection of the pressure cylinder(s) are kept 
free from damage. 
Further, impairment of the view of the driver is removed. 
By means of the accessibility of the locking pins from the seat of the lift 
truck, leaving the driver's seat is no longer necessary for the change, 
removal or installation of an implement. The seat switch is no longer 
opened, and the hydraulic system is not cut off. If the implement carrying 
frame is correspondingly positioned in regard to the implement to be 
affixed, and if the carrying frame has grasped it, then it can be 
immediately locked in place.

A DESCRIPTION OF ADVANTAGEOUS EMBODIMENTS 
FIG. 1 shows, in a schematic side view, the front area of a lift truck 
(truck omitted) with an installed lift apparatus 10 having two hydraulic 
lift and lower arms 11 and 12, of which FIG. 1 shows in detail arm 12, 
which is on right side as one faces the front of the said lift truck. The 
left arm 11 shows less detail. On the forward ends of the two power arms 
11 and 12 an implement carrier framing 15 is provided, which is hingedly 
affixed to the power arms (11, 12) by a pivot pin 18 located at right 
angles to the direction of lift truck travel. The implement carrier frame 
(15) is rotatable about said pivot pin 18, so that said carrier can be 
brought into an operating position for either lifting or lowering by a 
hydraulic cylinder 13 (only schematically shown) which grips with its 
piston rod a traverse 17 of the implement carrier frame 15. 
The implement carrier frame 15 possesses in its upper area, inclined 
shaping 32 conforming to implement 16, which said implement is provided 
with a connection piece 30 and grips the implement carrier frame 15 with 
its retaining hooks 31. On the underside of the implement, connection 
piece 30 is provided with diagonal struts 33 which fit into a 
correspondingly inclined under edge 35 of the implement carrier frame 15. 
Implement carrier frame 15 and connection piece 30 are put in a latch-in, 
latch-out mode, with the aid of two locking pins 34 set at each side on 
the implement carrier 15. In this way, the borings 36 in the inclined 
struts 33 align with the corresponding borings 36 in the area of the under 
edges 35 of the carrier frame 15, and it is into these borings that the 
locking pins 34 will be inserted. These pins 34 are pressed, pairwise, 
into the borings 36 of the diagonal struts 33, so that the locking nose 
34.1 can penetrate into this aligned boring 36. 
In this procedure, the locking pins 34 can be manipulated by means of 
pressure cylinder 40 which is connected to the onboard hydraulic system 
(see FIG. 7) through the hydraulic connections 55 to the pivot pins 18 as 
well by the control module 58 in the cab for the activation of the locking 
pins 34. These locking pins 34, because of space saving reasons, are 
located in the forward zone of the implement carrier frame 15. They are, 
by means of a power reversal device 38, moved out of a locking position 
into a released position and vice versa. 
The pivot pin 18 is, on each side, conducted through a boring 20 in a power 
arm (here power arm 12, analogously for power arm 11) and on through a 
second boring in the side wall of the implement carrier frame 15. The end 
of the pivot pin 18 which confronts the implement carrier frame 15 is 
designed with a segment conical in shape (see FIG. 2) which fits with 
close tolerance into a corresponding conical boring 22 in the implement 
carrier frame 15. On each side, an external, retaining plate 19 with 
boring, and affixed with screws 19.1 (only indicated), respectively 
overlaps the power arm end of each pivot pin 18, which end is reduced in 
diameter, and so assures maintenance of position for that said pin 18. The 
end of the pivot pin 18, which is conically received in the implement 
carrier frame 15 protrudes from said boring. The pivot pin 18 is provided 
with a through penetrating. axial boring 18.1, which is designed in the 
power arm side end accepts a screwed hydraulic connection. The receiver 
side end exhibits, as an exit, a screw fitting 18.2 for a hydraulic 
coupling. 
In another embodiment, the pivot pin 18 is designed as a cylindrical insert 
member (FIG. 2b) A firmly affixed plate 19 holds it in position. The inner 
end of the pivot pin 18 is rotatably seated in a bushing 25 and sealed 
against loss of grease by a stuffing means 25.1. The inner end of this 
said pin is further provided with a screwed in hydraulic fitting 18.2 to 
which a flexible tube is connected, by means of which, the hydraulic fluid 
is conducted to the pressure cylinder 40. 
If, in the case of relatively narrow lift trucks, a completely penetrating 
pivot shaft 50 is provided, then the ends thereof form the pivot pins 18, 
which are inserted through the borings 20 or 21 of the power arms 11 and 
12 as well as through the side walls of the implement carrier frame 15. 
Because of the single penetrating, cylindrical pin boring, both reduced 
diameter ends of the pivot pins 18 are secured by retaining plate 19 and 
with screws (only indicated) 19.1. The implement carrier frame 15 is 
hingedly linked onto the power arms with these pivot pins 18. 
The hydraulic feed is analogous: If the pressure cylinder 40 is single 
action, then one axial boring 52 is sufficient. 
If the pressure cylinder 40 is double action, then a pair of borings in 
opposite axial direction to one another are provided, whereby it is 
obvious, that the hydraulic exit ports from the pivot shaft 50 are 
correspondingly equipped. Thus, in the simplest case, the exit connections 
18.2 are installed directly at the opening positions of the radial borings 
53 which are set on the outer casing of the pivoting shaft 50. Of 
advantage is a rotatable exit fitting sleeve 60,which circumferentially 
encompasses the continuous pivot shaft 50 in the area of the of the radial 
borings 53 which open into grooves 53.1 and which enables an uncoupling of 
the pivoting movement. This removal sleeve 60 can exhibit ring grooves 61 
corresponding to the ring grooves 53.1 of the pivot shaft 50, which in 
turn are connected by radial borings 62 to the hydraulic exit screw 
connection ports 18.2 which are installed upon the outer surface of the 
removal sleeve 60. Internal ring sealant means assure that the grooves 
53.1/61 are tight against each other, as well as tight against the outer 
environment. Washer type blocking disks 65 on both sides assure the 
position of the removal sleeve 60. 
Because of the limited space relationships in the front area of a lifting 
truck, with implement carrier framing 15 hingedly linked on the power arms 
11 and 12, it is advantageous to arrange the motion axes of the locking 
pins 34 parallel to the piston rod 40.1 of the pressure cylinder 40. This 
permits an arrangement of the locking pins 34 independently of the 
pressure cylinder 40 near the front side of the implement carrier framing 
15. For the power transmission from the pressure cylinder 40 to the 
locking pins 34, advantageously, a power reversal apparatus 38 has been 
provided. 
In this matter, that is, of the power reversal apparatus, a mechanical 
structure in the form of, respectively, a V-shaped yoke (FIG. 4a), a 
U-shaped yoke (FIG. 4b) with a counterpoised simple lever (FIG. 5). 
Compound levers can be accordingly used, without limitation thereof. 
The lock-in apparatus 38 with locking pins 34, shows a hydraulic 
pressurized cylinder 40, (here shown as single acting) which cylinder is 
fastened and reinforcingly supported on the implement carrier frame 15. 
This cylinder 40 is connected to the on-board hydraulic system of the lift 
truck over the hydraulic lines 56 as well as 55. In order to arrange the 
locking pins 34 in the absolute front part of the implement carrier frame 
15, the axis of the pressure cylinder is installed parallel to that of the 
locking pins 34, which are activated by the power transmission (or 
lock-in) apparatus 38. 
For the sake of synchronization of the movement of the locking pins 34, 
both the hydraulic lines 56 (See FIG. 7) which feed the pressure cylinder 
40, emanate from the output ports of respective hydraulic apportionment 
means 57 which means is inserted in the line following the hydraulic exit 
port 18.2. In the case of a single acting pressure cylinder, the unlocking 
movement is controlled by pressure and the locking movement is activated 
by one of the locking movement return springs, wherein the spring can also 
be located in the pressure cylinder assembly. 
In one embodiment of the power transmission apparatus 38, the movement of 
the pressure cylinder 40 is transferred on a V-shaped yoke, which is 
connected to the piston rod 40.1 of the said pressure cylinder 40. The one 
leg 41 of the yoke extends to the locking pin 34, while another leg of the 
same 42 shows a guide bar 48 arranged parallel to the locking pin 34, 
which, to avoid canting or hang-up moves in a guide enclosure 49. In 
another embodiment, the yoke is U-shaped in structure. The apex of the 
U-bend 43 is connected to the piston rod 40.1 and transfers the motion of 
said rod to the locking pins 34 and the guide bar 48. 
In yet another embodiment of the power transmission apparatus 38, the 
motion of the pressure cylinder is transferred over a counterpoised lever 
arrangement 45. In this case, the piston rod 40.1 acts upon the short arm 
46 of a simple lever, the longer lever arm 47 of which operates in 
conjunction with the locking pin 34. Because of the pivoting movement 
about the fulcrum of the lever, here the locking pin 34 is pivotally 
connected to the lever by means of a slide ring guided in slit 47.1, 
compensating for the radial to linear motion. In both cases, the length 
relationship of the two lever arms 46 and 47 defines the transfer of power 
and travel. A short thrust cylinder requires a short lever arm 46. At the 
same time, for the locking pins 34 on the long lever arm, the longer path 
for unlocking is possible, and the necessary greater power can be obtained 
from the hydraulic cylinders. In order to prevent interfering, and thus 
undesired hang-ups in the movement of the locking pins, the guide 49 is 
designed to compensate for this. The guide 49, wherein guide bar 48 moves, 
possesses an axis parallel to the axis of the locking pin. This 
parallelism is important for a disturbance free operation. In this way, 
lateral movement is avoided. although even without lateral displacement, a 
guidance means, as shown in FIGS. 5, 6, can prevent jamming. 
A further possibility of the transfer of power lies in the rack and pinion 
drive. In the presentation chosen, the pressure cylinder 40 acts through 
the piston rod 40.1 and a coupling shackle 40.2 connected to a gear wheel 
44, whereby the shackle 40.2 is eccentrically linked to the gear wheel 44. 
The gear wheel 44 interacts with the locking pin 34.1 which is extended as 
a gear rack 34.2. When the pressure cylinder (in the presentation--FIG. 
6--shown as extended) is pressurized, then the piston rod 40.1 extends 
outwardly and carries along the coupling shackle 40.2. This turns the gear 
44 counterclockwise. In this way, the rack 34.2 of the locking pin, as 
well as the locking pin itself are brought into the locking position. The 
unlocking is done in reverse order. With such a gear transmission, the 
travel and power can be adapted to suit the local requirements of an 
application, wherein the axes of the pressure cylinder 40 and the locking 
pin 34 can also lie angularly displaced to one another. Obviously, in this 
way, instead of a single gear wheel being interposed, also a chain of 
several gears can be provided. Further, also in this case a jamming 
prevention guide 49 is provided, namely, the extension 48 of the locking 
pin 34 is thereby guided. 
Advantageously, the power reversal apparatus is provided with a power 
storage means. This becomes compressed upon locking and which, upon the 
loss of hydraulic pressure maintains the locking pin in--or transfers it 
to--the locked position. With this feature, an unexpected release of a 
raised implement upon loss of hydraulic system pressure is prevented, thus 
improving the operational safety. Such a power storage is, for instance, a 
spring 37. For the unlocking, the pressure cylinder 40 is pressurized, 
whereupon the piston rod 40.1 withdraws, lifting the yoke with its side 
42, or, in the case of the U-bow 43, and also lifting the locking pin out 
of the boring 36 in the connection piece 30 of the implement 16. Upon the 
motion of the thrust of the piston rod 40.1, for instance, a spring within 
the pressure cylinder will be compressed, so that sufficient force is 
available for the locking of the implement 16 in position by means of the 
locking pins 34. This is the case then, during a failure of hydraulic 
system pressure or loss of pressure to the pressure cylinder. If the 
hydraulic cylinder 40 is designed as a double action cylinder, then the 
piston itself can be exposed to pressure from both sides with hydraulic 
fluid. In this case, the unlocking of the locking pins 34 can be effected 
by withdrawal as previously described, as well as the locking by means of 
hydraulically setting the locking pins 34. 
In order to bring, or hold, the locking pin 34 in its locked position upon 
pressure loss or hydraulic failure, externally arranged springs 37 are 
advantageous and so located that they can be monitored. Such springs are 
backed up by a fixed washer or plate 37.1, thus at one end affixed to the 
structure, to act on a movable part of the power reversal apparatus 38. In 
FIG. 4a, the spring 37 is a compression spring which is compressed upon 
locking, and which, upon loss of pressure, expands and presses the yoke 
with the locking pin into the locking position. In FIG. 4b the spring 37 
is designed as a tension spring, which grips upon the bow 43 of the yoke 
and upon unlocking, retracts upon itself. Upon loss of pressure, this 
spring 37 draws the yoke with locking pins into the locked position. 
FIG. 5 and FIG. 6 show the spring 37 which interacts with the extension 48 
of the locking pin 34. In FIG. 5, this spring is designed as a tension 
spring, and with its secured end fixed on the guide 49, while the free end 
is connected with the extension 48 with the movement of which, said spring 
is carried along. In this case, this spring 37, upon unlocking is 
recognizably extended and so in tension. In FIG. 6, the spring is designed 
as a compression spring, with its fixed end on an abutment washer 37.1 
fixed to the structure while its free end is carried along with the head 
of the extension 48 of the locking pin 34. Obviously, in this case the 
spring 37 is pressed together upon unlocking, i.e. compressed. Upon 
hydraulic or pressure failure, the compressed spring 37 releases itself 
and forces before it the locking pins 34 into the locking position. 
FIG. 7 presents, finally, the schematic piping diagram of the on-board 
hydraulic system with attached pressure cylinder 40 for the 
locking--unlocking of the implement with the help of the locking pins 34. 
Hydraulic fluid is propelled from the hydraulic pumps 59 of the on board 
system into an accumulator 59.1, which has available several exit ports, 
(here only one is shown). The hydraulic cylinders 40 for 
locking--unlocking of an implement are here regulated by a 4/2 control 
valve 58. The said control valve 58 feeds the connection line 55 with the 
hydraulic fluid under pressure through the axial boring 52 in the pivot 
pins 18 and the hydraulic connection line 56, as well as the pressure 
cylinder 40 over the hydraulic apportioner 57, which possesses two 
branches. The pistons are accordingly put in motion and the piston rods 
40.1 (see FIG. 1) are withdrawn or extended. The release of pressure by 
reversal of the valve 58 reverses the direction of movement (if necessary, 
by the internal springs)and allow the pistons to return to their original 
positions.