Cylinder mounting

A shovel linkage for a hydraulic excavator includes boom rails having pivot means in one end for pivotal connection to an excavator and cross tubes extending between the rails near the pivot means and having pivot joints provided thereon for connection of actuating cylinders for the linkage in line with the cross tube and close to the pivot means whereby forces imparted to the linkage by the actuating cylinders will be directly through the center of the cross tube and very near the boom rail pivot means, minimizing bending moments in the linkage. The pivot joint includes a flat tab member provided on the cross tube and projecting outwardly along a diameter thereof, and a pin and ball connecting the bifurcated end of a hydraulic cylinder to the tab for limited rotation thereof. The pin is disposed substantially normal to the plane of the boom rails for unimpeded insertion and removal thereof.

BACKGROUND OF THE INVENTION 
This invention relates to the field of shovel linkages for hydraulic 
excavators and the like, and more particularly to the means for mounting 
the actuating cylinders thereof to the linkage. Typically such linkages 
comprise a link, generally known as a boom, pivotally mounted on the frame 
of the excavator, and a second link, known as a stick, pivotally mounted 
on the distal end of the boom, and having an implement, such as a bucket, 
pivotally mounted on the distal end thereof. The bucket is manipulated 
both vertically and horizontally in the plane defined by the boom and 
stick by pivotal movement of the boom with respect to the frame, the stick 
with respect to the boom, and the bucket with respect to the stick. Such 
actuation is effected and controlled by means of hydraulic actuating 
cylinders pivotally interconnecting the bucket and the stick, the stick 
and the boom, and the boom and the frame of the excavator. Such cylinders 
are typically connected to suitable brackets affixed to and projecting 
from these members. During the work cycle of a large shovel, it is 
necessary for the hydraulic actuating cylinders to apply large loads to 
the linkage members through the brackets or other attachment means by 
which they are connected to such members. Due to the manner in which the 
cylinders are secured to the shovel linkage members in prior art designs, 
moment arms exist which cause the cylinders to induce large torsional 
loads in the linkage members, which may lead to early fatigue of portions 
thereof. 
SUMMARY OF THE INVENTION 
Accordingly it is an object of the present invention to provide a shovel 
linkage for a hydraulic excavator whereby the actuating cylinders thereof 
will impart loads to the members of the linkage in such a manner that 
torsional loads and bending moments are minimized. 
A further object of the present invention is to provide a shovel linkage 
with a cylinder mounting which provides for limited rotation of the 
cylinder during operation of the linkage. 
It is another object of the invention to provide a cylinder mounting which 
may be easily connected and disconnected. 
These and other objects and advantages are achieved by the present 
invention which comprises a shovel linkage having a boom and stick both 
comprising parallel rails joined by cross tubes having pivot joints 
provided thereon for pivotal connection of hydraulic cylinders thereto, 
for operation of the associated links. 
The cross tube mounting the stick actuating cylinder is provided on the 
boom near the pivotal attachment of the boom to the excavator for reduced 
bending moments. 
The pivot joint on the cross tube is provided in flat tab members which 
project outwardly from the cross tube in the plane of a diameter of the 
cross tube so that the forces imparted to the cross tube by the cylinder 
upon actuation thereof are directed along a diameter of the cross tube. 
The pivot joint comprises a bore provided in the cross tube tab member, a 
ball provided in the tab bore and having a pin bore therein, an actuating 
cylinder having a bifurcated end which embraces the tab and has a pin bore 
provided therein, and a pin disposed in the ball and cylinder pin bores. 
The pivot joint is constructed so that the pin is disposed along a line 
which projects between the rails for ease of insertion and removal without 
interference by the rails.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a hydraulic excavator embodying the present invention 
is shown generally at 10 as comprising an undercarriage 12, and a frame 14 
pivotally mounted thereon, which includes an engine compartment 16 and an 
operator's cab 18. Mounted on frame 14 and extending forwardly thereof is 
a shovel linkage indicated generally by the reference numeral 20. The 
shovel linkage includes a boom 22 pivotally mounted on frame 14 by means 
of pivots 24 and actuable with respect to the frame by means of a pair of 
hydraulic cylinders 26 pivotally mounted to the excavator frame 14 and to 
the forward end of the boom 22, and a hydraulic cylinder 27 pivotally 
connected to the frame and to the boom. 
Pivotally mounted to the forward end of the boom is a stick 28 which is 
actuable with respect to the boom by means of a pair of hydraulic 
cylinders 30 pivotally connected to the boom and to the stick as will be 
described hereinafter. 
Pivotally connected to the distal end of the stick is a bucket 32 which is 
actuable with respect to the stick by means of hydraulic cylinders 34 
which are pivotally connected to the forward end of the boom and to links 
36 and 38 which are pivotally connected to the stick and bucket 
respectively. 
Referring to FIG. 2, boom 22 comprises spaced parallel rails 40 and 42 
which are of a generally boxlike configuration and include side walls 44 
joined by top and bottom walls 46 and 48. Pivots 24 are provided in one 
end of rails 40 and 42 for pivotal connection of the boom to the excavator 
frame 14 as previously described. Additional pivots 50 are provided in the 
other ends of the rails for pivotal connection of the stick thereto. 
Rails 40 and 42 are interconnected by means of cross tubes 52 and 54. 
Referring to FIG. 3, the cross tubes comprise cylindrical members 56 which 
extend through appropriate openings in the side walls 44 of rails 40 and 
42 and are retained therein by means of flanges 58 secured to the 
cylindrical members immediately adjacent to the side walls of the rails. 
As shown in FIG. 6, cylindrical members 56 comprise arcuate members 60 and 
62 and a bracket member 64 which includes a tab 66 having a pivot bore 68 
provided therein for a pivotal attachment of a hydraulic cylinder thereto. 
Bracket member 64 also includes arcuate portions 70 and 72 which abut 
members 60 and 62, and a diametral portion 74 which extends inwardly of 
the cylindrical member and abuts a diametral backing member 76 which 
extends across a diameter of the cylindrical member and is abutted at the 
opposite side of the cylindrical member from bracket member 64 by the 
other edges of arcuate members 60 and 62. During assembly of the cross 
tube, the members are welded together at the junctures shown to provide a 
unitary member. 
It will be noted that diametral portion 74 of bracket member 64 and 
diametral backing member 76 define a diameter of cylindrical member 56 
which extends through the center of bracket member 64 coplanar with tab 
portion 66 and normal to pivot bore 68 provided in bracket member 64. It 
will also be noted from FIG. 1 that hydraulic cylinders 30 are 
longitudinally aligned with the diametral backing member in cross tube 52, 
and cylinder 27 is aligned similarly with the diametral backing member in 
cross tube 54. Accordingly, forces exerted on the cross tube members by 
the hydraulic cylinder connected thereto at pivot bores 68 will be 
directed through the centers of the cross tubes, and no unnecessary 
bending moments will be imparted to the cross tube or boom rails of the 
shovel linkage. In addition the force exerted on the cross tube by the 
hydraulic cylinder attached at pivot bore 68 will be directed along 
diametral backing member 76, resulting in greater strength in the cross 
tube and better distribution of the forces exerted by the hydraulic 
cylinder on the cross tube. 
However, as boom 22 is pivoted on the excavator frame by hydraulic 
cylinders 26, master cylinder 27 must pivot in a vertical plane with 
respect to the boom rails and cross tube 54 at the cylinder end attached 
to the cross tube tab 66. Also, when stick cylinders 30 are actuated to 
pivot the stick on the boom, they must pivot vertically with respect to 
the boom and cam tube 52 of tab 66. If the axis of pivot bore 68 in tab 66 
were horizontal to allow vertical pivoting of the cylinders thereabout, 
assembly and disassembly of the boom would be hampered since rails 44 
would interfere with insertion and removal of the pivot pin. 
Therefore pivot bore 68 is disposed in a generally vertical direction so a 
pivot pin may be inserted and removed without interference with the boom 
rails. 
To allow for limited pivoting of cylinders 27 and 30 in a vertical plane 
they are connected to tabs 66 by means of ball joints shown generally at 
80 in FIG. 6. 
Ball joint 80 includes a ball 82 disposed in bore 68 and having flattened 
faces 84 and 86 in abutting engagement with matching faces 88 and 90 
provided on portions 96 and 98 provided by a bifurcated end 102 of 
cylinders 30 and 27. 
Ball 82 is provided with a pin bore 104 which is aligned with similar pin 
bores 106 and 108 provided in bifurcated portions 96 and 98. A pin 110 is 
disposed in pin bores 104, 106 and 108 to complete the ball joint. 
The ball joints allow for the limited vertical rotation of the cylinder 
that is required during the working cycle of the excavator linkage. They 
also allow for any lateral rotation of the cylinder necessary to relieve 
any sideloading of the cylinders that might occur from different lateral 
dimension of the respective cylinder ends, or side deflection of the 
linkage as it is swung by the rotation of the frame on the undercarriage. 
Since the pin bore is outwardly aligned it can be machined in the assembly, 
and the pin inserted and removed without interference.