Specifications

GOLDCUP CONTROLS SERIES 800
8C HYDRAULIC STROKER
W/BRAKE & BYPASS VALVE
S23-12820 (Feature 00)
DESCRIPTION
DISASSEMBLY
See Figure 8C
REWORK OF WEAR PARTS
ASSEMBLY
See Figure 8C
The 8C control incorporates the brake and neutral bypass functions into the body of
the proportional hydraulic stroker. A brake spool, when energized, connects the brake
port to servo pressure. When de-energized, a spring shifts the spool, connecting the
brake port to tank. Servo pressure releases the brake. Another port, located on the
end of the brake valve, is closed by the energizing of the brake spool. When de-ener-
gized, this port dumps both pump system ports to the replenishing source, thus
bypassing the small flow generated by slight errors on zero position.
The operation is controlled in this manner: A metered servo signal is applied to the
brake spool. This signal is dumped when a slot in the servo plate aligns with a pas-
sage connecting to this spool. This occurs when the pump is on zero stroke. Another
signal is applied to a spool adjacent to the brake spool. This metered signal is con-
nected to a port controlled by the input command spool. This port is set to open to
tank when the input command is at zero stroke. The brake spool is thus de-energized
when BOTH the pump cam is at zero stroke and the rotary servo is at zero command.
If the pump is on stroke or the input is on stroke, the brake spool is energized.
For a description of the hydraulic stroker, refer to the 8A control description.
1. Remove screws (2) from control.
2. Remove control from pump.
3. Examine servo plate for excessive scratching on surface. Note if orifices in stem are
open. If servo plate is scratched or orifices appear to be plugged, remove plate and
servo stem by removing two soc. setscrews from plate, then alternately loosening the
two button hd. screws under the setscrews.
4. Remove retaining ring (4) and press the shaft assembly through the valve body.
5. Examine shoes (8) and (18) for contamination in balance pads and excessive
scratching on shoe faces. Note the two shoes are not identical and must be installed
in the proper position upon reassembly.
6. Remove the brake trimmer stop assembly (13) intact.
7. Remove the center trimmer screw (23) with the spool assembly and stop assembly
intact. Note: signal pressure setting is determined by the spring preload. Do not dis-
assemble or change unless setting is incorrect.
8. Remove tubing assembly (74). Remove bypass valve body (42) with fitting (44) and
piston (45). Remove elbow (73) with .0135 orifice (37) and fitting (38). Remove spools
(31) and (39).
9. Remove shoe (50), and spring (49).
10. Examine orifices (16) and (29) in body for contamination. Examine passages in
body for free flow.
11. Clean and examine all parts for breakage or evidence of abnormal wear.
All parts are to be inspected and be free of material defects, dirt, scratches, or any for-
eign material.
All parts are to be cleaned with a suitable cleaning solvent and all cores and passages
blown out with clean dry compressed air.
After cleaning and inspection, all parts are to be covered with a light film of oil and
should be protected from dirt and excessive handling until assembled onto the unit.
During assembly, lapped and ground surfaces should be kept lubricated and protected
from nicks or surface damage.
1. Install .031” orifices (29), checking to see that they clear the bore. Install the .018”
orifice (16) in body.
2. Apply pipe sealant and install 1/16 pipe plugs (28) in body as shown. Torque to 25
in.-lbs. (2.8 Nm)
3. Apply pipe sealant to the 1/8” pipe plugs (12) and install in the cover plate. Torque
to 100 in.-lbs. (11.3 Nm)
4. Thread trimmer locknut (22) all the way onto center trimmer screw (23). Slip back-
up washer (21), small dia. first, onto trimmer screw and against locknut. Using a 3/4-
16 hex nut, with a 1.030” (26.2mm) dia. x .030/.035” (0.76/0.89mm) deep c’bore, crimp
78
Part Description Rework
Servo plate face Fine stone to remove raised burrs & dings
Shear seal Fine stone to remove raised burrs & dings. Note:
grooves to supply balance pads must be present
and adequate.
Control cover Stone or lap inside face to remove raised burrs &
dings.
Spool Break sharp edges or dings.
Shoe Stone to remove raised burrs or dings.