Fluid line coupling for fluid actuated extensible structure

A lift truck having a particular type of upright, namely, a triple stage upright having a fixed upright section, two telescopic sections, and a load carrier mounted on the inner telescopic section. A primary lift cylinder and chain assembly is mounted from and elevatable with the inner upright section and is connected with the load carrier to elevate it with the inner section, and a secondary lift cylinder is supported from the truck and connected to elevate the telescopic sections with the primary cylinder and load carrier. A fluid conduit is provided between the primary lift cylinder and secondary lift cylinder, a first portion of the fluid conduit having a first valve interposed therein is operatively associated with the primary lift cylinder and is selectively engageable with a second valve interposed in a second portion of the fluid conduit and operatively connected with the secondary lift cylinder. When the primary lift cylinder is retracted relative to the secondary lift cylinder, the coupling comprised by the first and second valves is in its fluid engagement position, but is not in its fluid engagement position when the primary lift cylinder is extended. The coupling has self-centering alignment capability. Fluid retained in the second valve is protected from contamination by an overlying cover plate when the primary lift cylinder is extended.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to fluid couplings for fluid actuated extensible 
structure and more specifically to a hydraulic coupling in a hydraulic 
line of a lift truck upright. 
2. Description of the Prior Art 
Over the years a persistent problem in fluid actuated extensible 
structures, such as multi-stage uprights for lift trucks, has been to 
provide a construction which affords the operator of the apparatus good 
visibility through the structure. Heretofore, various means have been 
devised for improving operator visibility through lift truck uprights such 
as is disclosed in U.S. Pat. Nos. 2,855,071, 3,213,967, 3,394,778, U.S. 
Pat. No. Re. 27,731, and in copending U.S. Application Ser. No. 017,779, 
filed Mar. 8, 1979 now abandoned, all of which are assigned to the 
assignee of the present application. 
Generally, in the above-discussed prior art, as shown in FIG. 8 of 
Application Ser. No. 017,779, supra, fluid communication between a primary 
cylinder and a secondary cylinder is provided by a hose that is routed 
from the base of the secondary cylinder to the top of the upright, over a 
sheave and then back down to the base of the primary cylinder. 
Frequently the design of the upright dictates that the hose routed over the 
sheave at the top of the upright must bend below the minimum recommended 
bend radius which leads to shortened hose life. To minimize the bend 
radius the hose diameter can be reduced but this creates increased back 
pressure and adds inefficiency to the hydraulic system. Additionally, the 
above-described hose connection reduces visibility through the upright. 
SUMMARY OF THE INVENTION 
This invention solves the above-mentioned problems by providing a hydraulic 
coupling which includes a first valve mounted on a telescopic section and 
a second valve mounted on a relatively fixed section. The valves engage 
when a secondary hydraulic cylinder assembly is retracted longitudinally 
of the fixed section to cause the primary hydraulic cylinder assembly to 
be retracted relative to the secondary hydraulic cylinder assembly. The 
valves are disengaged when the secondary hydraulic cylinder assembly is 
extended longitudinally of said fixed section. 
The first valve of the coupling has a tapered outer end to assist 
registration with the second valve when the secondary hydraulic cylinder 
assembly is retracted longitudinally of the fixed section. Additionally, 
the second valve is flexibly mounted on the fixed section and is 
internally tapered to assist coupling registration. 
It is a primary object of this invention to improve operator visibility 
through a fluid actuated extensible structure. Other objects, features and 
advantages of the invention will readily appear to persons skilled in the 
art from the detailed description of the invention which follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The upright of the present invention is for use with any suitable lift 
truck (not shown). The invention is, however, broader than any application 
disclosed herein, it being applicable to any type or model of lift truck 
upright, two stage, triple or quad, for example, or to such devices as 
telescopic hydraulic crane equipment, or to any other mechanism wherein 
the fluid line coupling of my invention is applicable to permit separation 
of a fluid conduit which connects different hydraulic actuators when one 
actuator is actuated outwardly of a second actuator. One preferred 
embodiment of the present invention is shown in FIGS. 2-6 for an 
asymmetric triple stage upright which is described in detail in 
application Ser. No. 017,779, supra. 
The hydraulic circuitry for the present invention is shown schematically in 
FIG. 1. Hydraulic fluid is supplied from a fluid reservoir 12 through a 
suitable pump 14 and then through a control valve 16 to the primary and 
secondary lift cylinders 18 and 20 respectively, and to other 
hydraulically controlled functions such as upright tilt cylinders 22. A 
hydraulic conduit means 24 is adapted to connect primary and secondary 
cylinders 18 and 20 to fluid reservoir 12 through control valve 16 while 
conduit means 25 connects cylinders 22 to reservoir 12 through control 
valve 16. Branches 26 and 30 of conduit means 24 connect primary and 
secondary lift cylinders 18 and 20 respectively, to control valve 16 and 
to reservoir 12. A coupling 28 including a first valve assembly 34 and a 
second valve assembly 32 is interposed in branch conduit 26. Valve 34 is 
in fluid flow engagement with valve 32 when secondary cylinder 20 is in 
the retracted position shown in FIG. 1. 
Referring now to FIGS. 2-7, the triple stage upright assembly 40 comprises 
a fixed mast section 42 which includes a pair of transversely spaced 
opposed channel members 44 arranged to receive an intermediate telescopic 
mast section 46 formed of two laterally spaced I-beams 48, mast section 46 
being guide roller supported in mast section 42 and arranged for 
longitudinal movement relative thereto. An inner mast section 50 formed of 
two laterally spaced I-beams 52 is similarly guide roller supported in 
mast section 46 and arranged for longitudinal movement relative thereto. A 
load or fork carriage 54 having a pair of transverse support plates 56 and 
58 is guide roller mounted for elevation in the inner upright section 50, 
all in known manner. 
Mast section 42 is cross-braced for rigidity by means of upper and lower 
transverse brace members 60 and 62, intermediate telescopic section 46 is 
cross-braced by upper and lower transverse members 64 and 66, and inner 
section 50 is cross-braced by upper, intermediate and lower transverse 
members 68, 70, 71, 72, and 74, members 70 and 72 also serving to support 
the primary lift cylinder, as will be explained. 
The I-beam mast section 46 is nested within the outer section 42 in known 
manner such that the forward flanges of the I-beams 48 are disposed 
outside of and overlapping the forward flanges of channels 44, and the 
rear flanges of the I-beams are disposed inside the adjacent channel 
portions and forwardly of the rear flanges of channels 44, pairs of 
rollers 80 being suitably mounted between said adjacent pairs of the 
I-beams and channels for supporting the I-beam telescopic section 
longitudinally and laterally for extensible movement relative to the fixed 
channel section. In a similar manner, inner I-beam mast section 50 is 
nested within intermediate section 46 for extensible movement relative to 
the intermediate I-beam section. 
A first fluid actuator assembly includes a primary lift cylinder 18 
supported centrally of inner upright section 50 on brace members 70 and 72 
by brackets 82 and 84 secured, as by welding to the cylinder and secured 
by studs to the transverse members 70 and 72 (FIG. 2). A single sprocket 
86 is mounted for rotation by a bracket 88 at the end of a piston rod 90, 
a lifting chain 92 being reeved on the sprocket and secured at one end to 
an anchor plate 94 located on the cylinder, and which at the opposite end 
is secured centrally of carriage plate 58 by an anchor block (not shown). 
A junction block 114 is located at the bottom of the primary cylinder 18 
for conveying hydraulic fluid to and from the primary cylinder 18 by 
branch conduit 26. Lift cylinder 18 is substantially one-half the length 
of the inner upright section 50 and when extended actuates the fork 
carriage at a 2:1 ratio to a full free-lift position as shown in FIG. 3 
prior to the elevation of intermediate and inner upright sections 46 and 
50 by a secondary asymmetric hydraulic lift cylinder assembly 20 shown in 
a position of partial extension in FIG. 4. 
A secondary fluid actuator assembly includes secondary lift cylinder 20 
supported near the bottom from brace member 62 by a collar 102 welded to 
the cylinder, the piston rod 104 being secured by a pair of studs 108 to a 
block member 110 which is welded to the rear surface of brace member 64, 
thus supporting the cylinder assembly from the top and bottom portions. A 
junction block 112 is located at the bottom of the cylinder for conveying 
hydraulic fluid to and from the cylinder through branch conduit 30. 
A chain anchor block 120 is secured centrally of inner upright transverse 
brace member 72 at an anchor connection 122 of a secondary lifting chain 
124 which extends upwardly and over a pair of transversely spaced 
sprockets 126 and 128, and then downwardly to a fixed anchor connection 
130 located in a predetermined position adjacent the outer end of a 
step-down support and brace plate 132 of brace member 60, the horizontal 
end portions of brace 60 being connected by a vertical bar 134. The 
sprockets are mounted for rotation on stub shafts which are cantilever 
mounted in and secured to transverse brace member 64. 
As shown in FIGS. 5, 6 and 7 the first valve assembly 34 is connected to 
the intermediate transverse member 71 of innermost mast section 50. The 
first valve 34 includes a hollow tubular portion 160 tapered at its lower 
end 162 and having in its top surface 163 a port 164. Port 164 has a 
threaded housing 165 with a port opening 167 having an inner diameter 169, 
an outer diameter 171, and a chamfer 173, there between. Top surface 163 
of tubular portion 160 has a circular indentation 182 and an opening 184 
through which port 164 is threadably inserted. Tubular portion 160 has an 
inner wall 161 which has at its lower end 162 an inner frustro-conical 
shaped surface 200 for engagement with the upper frustro-conical shaped 
portion 201 of valve stem 202. Plunger 206 is integrally connected at its 
lower end to stem block 208 which is integrally connected to the upper 
portion 201 of valve stem 202. Washers 210 and cross-shaped guide 212, 
which has an upper rim 203, are spaced apart by a spring 204. Plunger 206 
is internally threaded through spring 204 and is inserted through bore 214 
in guide 212. When upper portion 201 of stem 202 is in seated engagement 
with the frustro-conical inner surface 200 of the lower end 162 of hollow 
tubular member portion 160, primary cylinder 18 is not in fluid 
communication with the hydraulic fluid reservoir. 
Second valve 32 of coupling 28 is attached to an extension plate 136 of 
brace member 62 by self-centering device 140 which includes a nut and bolt 
assembly 142, a retainer ring 144 having an inner cavity 146, and a 
circular endless spiral spring member 148 provided in the inner cavity 
146. Hollow cylindrical housing 150 of second valve member 32 has an outer 
flange 152 partially received in the inner cavity 146 of self-centering 
device 140 and is bias mounted by spring 148 in the retainer ring 144 of 
self-centering device 140. Tapered portions 154 of the upper inner 
peripheral surface of hollow cylindrical housing 150 combines with the 
self-centering device 140 to allow the lower tapered end 162 of first 
valve member 34 to register in fluid communication with the second valve 
member 32 even though the valves are not in exact alignment. A high 
pressure U-shaped seal 156 provided in a circumferential recess 157 in the 
inner surface of cylindrical housing 150 of second valve 32 prevents 
undesired fluid leakage when the coupling members are in fluid engagement. 
A dirt seal 166 is provided in the upper curled lip portion 180 of first 
valve 34 to prevent hydraulic fluid contamination. 
Second valve 32 includes an inwardly projecting circular flange 215 from 
the inner surface of housing 150 which has a frustro-conical surface 216. 
A stem 218 has a lower frustro-conical portion 220 in selective seated 
engagement with the inside surface 216 of inner flange 215 of tubular 
housing 150. Integrally connected to the bottom of stem 218 is a 
cylindrical rod 222 internally threaded through a spring 224 which is 
retained between upper washers 226 and a plug 230 which has an internal 
bore 228 to receive a downwardly directed vertical plunger 232 internally 
connected to rod 222. The spring 224 acts to bias the lower portion 220 of 
valve stem 218 into seated fluid blocking engagement with the inner 
surface 216 of flange 215. When first valve 34 and second valve 32 are in 
their FIG. 6 engaged positions both valve stems 218 and 202 are unseated 
and allow fluid communication between port 164 in the first valve 34 and a 
port 158 in the second valve 32. When the valves 34 and 32 are removed 
from their FIG. 6 position, valve stems 202 and 218 by the action of their 
respective springs 204 and 224 are returned to their respective seated 
position shown in FIG. 7. 
It should be noted that after first valve member 34 is retracted from fluid 
engagement with second valve member 32 a pool of hydraulic fluid remains 
trapped in the interior of tubular housing 150. To protect this pool of 
fluid from contamination from impurities, a cover plate 168 is pivotally 
connected at one end to a raised portion 170 of retainer ring 144 at 172. 
The other end 174 of the cover plate overlies the open end of valve 
assembly 32 when the innermost upright section 50 is raised from its fully 
lowered position shown in FIG. 2. The overlying end 174 of cover plate 168 
has a cap portion 175 which seals the second valve 32 from contamination 
when the cover plate is in its FIG. 7 position. 
The cover plate 168 includes a roller 176 mounted for rotational movement 
on the one end of cover 168 and engageable with a camming surface actuator 
178 connected with the innermost upright section 50. The lower end of the 
camming surface actuator 178 is spaced below the lower end 162 of the 
first valve 34 and engages the roller 176 to swing the cover plate 168 
upward and away from the second valve 32 when the innermost mast section 
50 is fully retracted. 
In operation, to elevate the upright 40 from the position shown in FIG. 2 
to that in FIG. 4, hydraulic fluid is delivered simultaneously to both 
fluid actuator assemblies and, as is well known, the primary and secondary 
cylinders operate automatically in a sequence related to the pressure 
differential in the cylinders whereby the primary cylinder 18 functions to 
elevate load carriage 54 to the full free-lift position illustrated in 
FIG. 3. At the termination of this initial stage of operation the 
hydraulic fluid automatically sequences secondary cylinder 20 to elevate 
the entire telescopic upright structure in known manner and as shown in 
FIG. 4 while the load carriage is maintained by cylinder 18 in the 
aforementioned free-lift position. 
When the load or fork carriage 54 is in a free-lift position and the 
secondary cylinder 20 is initially extended the valve assemblies or 
coupling members 32 and 34 are separated as in FIGS. 4 and 7 and assume a 
fluid blocking or no-flow position. As shown in FIG. 3 when the load 
carrier is in its free-lift position, the roller 176 of the cover plate 
168 is in engagement with the camming surface plate 178 attached to the 
left I-beam rail 52. When the secondary cylinder begins to extend, the 
camming surface actuator 178 moves upwardly away from the roller 176 and 
consequently the cover plate pivots at 172 to assume a horizontal 
overlying position above the second valve 32 of coupling 28 to protect it 
and the pool of hydraulic fluid above flange 215 from foreign elements 
such as dirt and grease when the coupling members are disengaged. 
Lowering of the upright is effected by actuating the control valve 16 to 
vent the secondary cylinder to the fluid reservoir, whereby a reversal of 
the above-mentioned sequence occurs as cylinder assembly 20 first fully 
retracts from the position shown in FIG. 4 to the FIG. 3 position, where 
the camming surface actuator 178 again engages roller 176 of cover plate 
168 to swing the cover plate upwardly away from the second valve 32 so 
that first valve 34 can again engage second valve 32 to establish fluid 
communication. 
As will now be apparent to persons skilled in the art, my invention 
provides much improved operator visibility through lift truck uprights and 
the like by eliminating, or at least minimizing, the previous requirement 
for flexible hose and the reeving thereof in the upright. 
Although only one embodiment of my invention has been described herein, 
this disclosure is merely for the purpose of illustration and not as a 
limitation of the scope of the invention. It is therefore to be expressly 
understood that the invention is not limited to the specific embodiment 
shown, but may be used in various other ways, and that various 
modifications may be made to suit the different requirements, and that 
other changes, substitutions, additions, and omissions may be made in the 
construction, arrangement, and manner of operation of the parts without 
necessarily departing from the scope of the invention as defined in the 
following claims.