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COMPONENTS CX130
CASE TRAINING CENTER
AUGUST 2000
Foot control
In neutral the foot control is a closed center hydraulic valve. The inlet oil from the pilot pump is blocked at both
regulator spools (17 ). The ports (1), (2), (3), (4) are ported inside of the valve back to tank through a hole drilled
in the end, and a cross drilled hole in the regulator spool (17).
There are two springs (20) and (21) for each regulator spool (17). The larger diameter spring (21) provides the
return of the foot pedal and this spring (21) is the resistance the operator feels in his foot.
Typically the return springs are stronger in foot control than in hand control.
If the dust cover (30) under the foot control is torn, replace it. This will help prevent contamination from wearing
the U-seals (6) on the push rods (8).
The gap between the push rod (8) and the screw (28) can be adjusted. A too tight adjustment can cause partial
actuation of the spool. The contact area between the push rod (8) and the screw (28) should be lightly lubricated
with grease.
How it work
As the foot control is moved, the push rod (8) will push on both large and small diameter springs (21 & 20). The
smaller spring (20) will push the spool (17) and block of the return passage through the top meetering notches.
The bottom metering land will open a passage and allow pilot oil out to the work spool of the travel control spool.
As the travel spool moves and compresses the spring in the control valve, the pressure will increase and push up
on the bottom of the regulator spool (17). When the pressure of the oil pushing on the travel spool equals the
force of the spring (20) behind the regulator spool (17) the bottom metering land will block the pilot supply. When
the force of the spring (20) equals the force of the pressure on the spool (17), the spool (17) is in a balanced
position to maintain a proportional pressure with the compression of the spring (20).
The foot control must be moved further to compress the small spring (20) and push the regulator spool (17)
further to increase the pressure again.
The foot control is nothing more than an adjustable pressure regulator, and the operator provides adjustment .
1Body
2>Plug
3>Mounting braket
4>Bushing
5>Seal cover
6>U-seal (retainer)
7>O-ring
8>Push rod
9>Spring cup
10>Spring guide
11>Spring cup
12>Snap ring
13>Ball seat
14>Piston
15>Ball
16>Bolt
17>Regulator spool
18>Spring cup
19>Shim
20>Regulator spring
21>Spring (feel lback)
22>Spring
23>Spring
24>Bushing
25>Shaft
26>Cam
27>Bolt
28>Adjustement bolt
29>Nut
30>Rubber boot
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