Specifications

GOLDCUP CONTROLS SERIES 500
CODE 5C - ELECTRIC
STROKER WITH BRAKE AND
BYPASS
S23-12414 - 5C* 00 (With Deadband)
S23-12420 - 5C* 01 (No Deadband)
DESCRIPTION
DISASSEMBLY
See Figure 5C
NULL ADJUSTMENT:
This control is used on pumps. The rotary servo input shaft is actuated by a hydraulic
spool. A jet pipe is directed to two receiver orifices connecting to opposite ends of the
hydraulic spool. The jet pipe is mechanically centered by a null adjust spring opposed
by a feedback spring linked to spool position. A “voice coil” attached to the jet pipe
creates an unbalance force in proportion to electrical current magnitude and direction.
This causes the jet pipe to offset, increasing pressure on the one receiver and lower-
ing pressure on the other receiver. The hydraulic spool responds causing the feedback
spring to oppose the force, until the jet pipe is again centered at a new position of the
servo.
When servo pressure to the jet pipe is blocked, the rotary servo spring centers, and
may be manually positioned.
One version of the cross center control requires a small signal (deadband) prior to
commencing stroke in either direction. This control contains spring centering pistons
and neutral trimmer adjustment for accurate centering. Another version, (no deadband)
provides linear displacement with input command for accurate servo applications.
In the control cover is contained the brake and bypass valve option. 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. 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 restricted servo flow is applied to shift
the brake spool. This flow 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
restricted flow is applied to a spool adjacent to the brake spool. This flow is also con-
nected to a passage in one centering piston, containing a ball and seat. When the
control is off center, the ball seats, sealing the passage, to apply servo pressure to the
spool. When the control is on center, a pin extending from the other centering piston
pushes the ball off the seat, to dump the flow,
The brake spool is thus de-energized to set the brake 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, releasing the brake.
If control functions over its full range, but pump remains on stroke when there is no
electrical signal, adjustment of null position is indicated.
1. Load pump. Set compensator to 1000 psi (69 bar). Shut off external servo supply
to control.
2. If system contains a shuttle valve, disable the shuttle valve as follows:. If shuttle is
on the pump, turn the shuttle relief adjustment two turns in. If it is a Denison shuttle
mounted on the motor, remove shuttle and plug the two threaded ports with 3/8-24
setscrews. Re-install the valve.
3. Adjust and lock the trimmer for minimum system pressure on both ports. Connect a
handle to the .375” (9.52 mm) dia. shaft extension on the stroker. Stroke the pump
both sides of center. Do not exceed 100 lbs-in. (11.3 Nm) torque. Observe pressures
on system ports when handle is released. Continue adjustment till pressure on either
side is less than 150 psi (10.3 bar) difference.
4. To set jet pipe null adjustment, disconnect electrical signal and open servo oil supply
to stroker. (200 psi min, 1000 psi max.) (14 bar min. 69 bar max.). For pump controls
with deadband, rotate the jet pipe null adjustment CCW and CW to develop 700 psi
(48 bar) on each system port. Caution: always begin adjustment by backing out
(CCW) on the jet pipe null adjustment and observing control reaction.
Overadjusting clockwise direction can damage the jet pipe or the trimmer
spring. Set and lock the screw midway between these two limits. Torque to 10 lbs-in.
(1.1 Nm) max. Install O-ring and cover nut.
5. For pump controls with no deadband, set and lock the jet pipe null adjustment at
the point of minimum system pressure on both ports with pump at operating tempera-
ture.
36
Note: This control is precision manufactured and requires training to properly
assemble or disassemble. Unless repair parts and factory trained personnel
are available, service should be limited to the brake and bypass portion, and
null adjustment