Gauge structure for a cylinder operated depth control

A stroke limiting structure for use with a lift control system on an implement includes a reciprocating link operably connected to a hydraulic cylinder and to a lift wheel assembly on an implement frame section. The link is connected by a lost motion connection to depth gauging structure including gauge plates pivotally supported on a carrier. The plates are rotatable between disengaged and engaging positions without need for tools and are maintained together on the carrier to eliminate loose parts that could be misplaced or lost. The plates in the engaging position determine the lowermost position of the implement and provide a positive mechanical stop for the implement to eliminate depth control problems caused by cylinder leakage or the like. The lost motion connection eliminates unwanted movement of the plate carrier and facilitates gauge plate pivoting for depth adjustments.

BACKGROUND OF THE INVENTION 
1) Field of the Invention 
The present invention relates generally to agricultural implements and, 
more specifically, to a depth control adjustment for cylinder operated 
lift system on an implement. 
2) Related Art 
Hydraulically operated lift structures on an agricultural implement often 
include hydraulic or mechanical stops to adjust position of the 
implements. For example, on tillage and seeding equipment frames, 
hydraulic depth controls of the type shown and described in U.S. Pat. Nos. 
5,427,184 and 5,366,024 provide adjustable hydraulically operated down 
stops but require relatively complex linkage arrangements. Series cylinder 
hydraulic systems are also commonly utilized, but cylinder or other system 
leakage can adversely affect the depth setting in systems which require 
cylinder pressure to hold a preselected depth setting. Various mechanical 
stop systems, such as cylinder collars or donuts placed over the rod of a 
hydraulic cylinder provide a solid mechanical stop, and the number or size 
of the collars can be changed to adjust implement position. However, such 
adjustments are time-consuming, particularly if the cylinder is located in 
a position that is hard to access. Small changes in implement position are 
often difficult to achieve with many of the previously available, and 
individual adjusting components usually require a separate storage area 
and are easily lost or misplaced. Heretofore, providing a relatively 
simple and inexpensive mechanical stop that is reliable and yet easy to 
adjust for different implement positions has been a continuing problem. 
BRIEF SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an improved 
implement position control structure. It is a further object to provide 
such a structure which overcomes most or all of the aforementioned 
problems. 
It is a further object of the present invention to provide an improved 
implement position control structure for a hydraulically operated system 
which is relatively simple and inexpensive and yet is easy to adjust. It 
is another object to provide such a structure which obviates cylinder 
collars and provides a large number of position mechanical settings 
without loose parts that could be easily lost or misplaced. It is still 
another object to provide such a structure which can be adjusted without 
tools and without removing or adding components. 
In accordance with the above objects, a stroke limiting structure for use 
with a lift control system on an implement includes a reciprocating link 
operably connected to a hydraulic cylinder and to a lift wheel assembly on 
an implement frame section. The link is connected by a lost motion 
connection to depth gauging structure including gauge plates pivotally 
supported on a carrier. The plates are easily rotatable between disengaged 
and engaging positions without need for tools and are maintained together 
on the carrier to eliminate loose parts that could be misplaced or lost. 
The plates in the engaging position determine the lowermost position of 
the implement and provide a positive mechanical stop for the implement to 
eliminate depth control problems caused by cylinder leakage or the like. 
The lost motion connection eliminates unwanted movement of the plate 
carrier and facilitates gauge plate pivoting for depth adjustments. 
These and other objects, features and advantages of the present invention 
will become apparent to one skilled in the art upon reading the following 
detailed description in view of the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring now to drawings, therein is shown an implement 10 having a 
plurality of frame sections 12, only one of which is shown, each with a 
pivoting lift wheel structure 14 having ground wheels 16 supporting the 
implement 10 for forward movement over the ground. A lift control system 
20 is connected to the lift wheel structure 14 for raising and lowering 
the frame section 12 between transport and field working positions and for 
adjusting the working depth when the section is in the field working 
position. Trailing wheel structures 24, shown in FIG. 1 as press wheels 
pivotally supported at locations 26 and 28 from the frame section 12, are 
adjustable to control the height of the aft end of the frame section. 
The lift control system 20 includes fore-and-aft extending link structure 
30 at least partially contained within an end support tube 32 of the 
section 12. The link structure 30 includes a forward link 34 connected to 
a lift arm assembly 35 on the lift wheel structure 14 for pivoting the 
structure 14 to raise and lower the wheels 16 relative to the frame. The 
link structure 30 also includes an aft link 36 connected by a slotted lost 
motion connection 38 to the aft end of the forward link 34. 
A crank assembly 40 (FIG. 1) is pivotally connected to the aft crank of the 
section 12 for rocking about an axis transverse to the forward direction. 
The crank assembly 40 includes an inner upright arm 42 connected to a rod 
end of a hydraulic lift cylinder 44 having a base end connected to the 
frame section 12. An outer arm 46 is connected for rocking with the inner 
arm 42 about the transverse axis as the cylinder 44 is extended and 
retracted. Pivot structure 48 connects the upper end of the arm 46 to the 
forward link 34 to move the link 34 generally in an axial, fore-and-aft 
direction within the tube 32. As the link 34 is moved forwardly by 
retraction of the cylinder 44, the lift arm assembly 35 pivots to raise 
the wheels 16 relative to the frame section 12 and lower the implement 10. 
Extending the cylinder 44 moves the link 34 rearwardly to pivot the 
assembly 35 in the opposite direction to raise the implement 10 towards a 
transport position. 
Adjustable stroke limiting structure 50 is connected to the aft link 36 to 
limit the movement of the link 34 in the forward direction to thereby 
provide an adjustable positive mechanical stop to set the lowermost 
position or working depth of the implement 10. The lost motion connection 
38 allows the forward link 34 to move with extension and retraction of the 
cylinder 44 while a substantial portion of the stroke limiting structure 
50 remains relatively stationary on the frame section 12. The connection 
38 also facilitates easy adjustment of the stop position of the link 
structure 30, as will be described in detail below. 
Referring to FIGS. 2 and 3, the aft link 36 supports the limiting structure 
50 and includes a rod member 54 fixed to a pair of transversely spaced, 
slotted side members 58. The members 58 are pinned by pivot structure 60 
to the aft end of the link 34 to define the lost motion connection 38 
between the link sections. The rod member 54 is slidably received through 
a pivot block 64 connected for rocking about a transverse axis to inner 
support plates 66 mounted within an aft tube section 32a. Pairs of cap 
screws and washers 68 mount upright supports 70 on the outsides of the 
tube section 32a and secure the inner support plates 66 in position. A 
spring 74 is compressed between the pivot block 64 and the slotted members 
58 to bias the rod member 54 to the left as viewed in FIG. 3. An end plate 
or plate carrier 78 is screwed onto the aft threaded end of the rod member 
54, and a pin 80 inserted through a small bore at the threaded end 
maintains the plate 78 in an upright position. An operator handle 82 is 
secured to the plate 78, and a cap screw or pivot 88 projects forwardly 
through an upper aperture in the plate. A plurality of generally flat 
gauge or adjusting plates 90 (FIG. 3) are mounted on the pivot 88 for 
individual rotation about the axis of the pivot between an upper 
disengaged position (see plates 90d of FIG. 2) and a lowered engaging 
position (90e of FIG. 2). A plate retaining spring 96 (FIG. 3) is secured 
over the forward end of the pivot 88 by a lock nut and washer 98 to 
maintain the plates sandwiched together between the spring 96 and the 
forward face of the end plate 78. 
Each of the plates 90 includes a tab 100 on the end opposite the pivot area 
(indicated generally at 102), and a notch 104 conforming generally to the 
shape of the rod member 54. The center of the notch 104 and the center of 
the rod member 54 are offset approximately an equal distance from the 
pivot 88 so that as a plate 90 is rotated approximately 180 degrees in the 
clockwise direction (as viewed in FIG. 2) from the upper disengaged 
position 90d to the lowered engaging position 90e the notch 104 will move 
over the rod member 54. The pivot area 102 preferably includes mating 
indentations and protrusions which engage in both the disengaged and 
engaging positions and are maintained in contact with each other by the 
bias of the spring 96 to help retain the plates 90 in the selected 
positions. The disengaged plates 90d are retained between the insides of 
the upright supports 70 as the rod member 54 is urged to the left by the 
bias of the spring 74. The engaging plates 90e form a solid mechanical 
stop as they are sandwiched in order between the pivot block 64 and the 
forward face of the end plate 78. 
As the cylinder 44 is retracted, the link 34 moves forwardly, and the frame 
section 12 lowers as the wheels 14 move upwardly relative to the frame 
section. The pivot structure 60 of the lost motion connection 38 between 
the links 34 and 36 slides forwardly in the slots of the side members 58 
(FIG. 3) until the structure 60 bottoms against the forward end of the 
slots. The link 36 then mechanically retains the wheel structure 14 in the 
lowered position which is determined by the number of the plates 90e in 
the engaged position. Preferably, the cylinder 44 includes a pressure 
responsive bypass valve 44p to limit pressure on the lift linkage when the 
linkage bottoms against the adjustable stop and to provide continued flow 
to any series connected cylinders on linkages not yet bottomed against 
their stops. 
To adjust the lowermost working position of the section frame 12, the 
operator simply extends the cylinder 44 to raise the frame section and 
remove tension from the link 36. The operator then pulls the handle 82 to 
move the rod member 54 rearwardly (to the right) and rotates the plates 90 
about the axis of the pivot 88 to change the number of plates in the 
engaging position 90e and thereby change the axial position of the rod 
member 54. The operator releases the handle 82, and the spring 74 firmly 
sandwiches the plates 90e between the end plate 78 and the pivot block 64 
to establish the stroke limit stop for forward movement of the link 34. 
The lost motion connection 38 thereby facilitates easy stroke limit 
adjustments without tools and reduces movement of the end plate 78 and 
handle 82 as the forward link 34 reciprocates within its adjusted stroke 
range. 
Having described the preferred embodiment, it will become apparent that 
various modifications can be made without departing from the scope of the 
invention as defined in the accompanying claims. For example, although the 
gauge plates are shown pivotally connected to a carrier on the rod member 
54, the plates may be pivotally mounted directly on the frame. Also, the 
gauge structure may be mounted adjacent or directly on the cylinder 44 
next to the cylinder rod so the plates 90 can be pivoted directly over the 
cylinder rod.