Specifications

GOLDCUP CONTROLS SERIES 500
rent and slowly apply the opposite polarity current to the valve. Note the value of cur-
rent at which pressure builds the opposite side of center (e.g. -50MA). The sum of the
absolute values must be between 50 and 100 MA (e.g. 40 + 50=90MA), and the differ-
ence between the two absolute values must be less than 20MA. (e.g. 50 - 40=10MA).
If not within specification, readjust jet pipe null.
For controls with the 01 feature (no deadband), there should be minimal hesitation as
the control signal passes through zero.
11. Apply 330MA to the control. The pump should go to full displacement. Repeat for
opposite side. With the “A” terminal positive, control shaft should rotate CCW.
12. With pump at full displacement, block the servo supply to the stroker. The pump
should spring center within 3 seconds.
13. Check for smooth change in displacement with gradual increase and decrease of
control signal.
14. Load pump. Stroke input shaft CW. The gage on the brake port should start to
indicate servo pressure when the system pressure is between 2000 and 4500 psi (138
and 310 bar), with an increasing signal, and must return to case pressure before sys-
tem pressure drops to 2000 psi (138 bar), on decreasing signal. Repeat by rotating
input shaft CCW. If pressures are incorrect remove piston assembly containing the ad-
justment screw, to change ball gap setting. Extend adjustment to increase pressures,
retract to reduce pressures. Standard setting is .012” (0.305 mm) gap, which is 3/8
turn of adjustment beyond closed position.
15. When finished adjusting, record both pressures for each rotation of the servo input
shaft.
16. Open the needle valve on the neutral bypass port. Measure and record leakage
from this port with the pump on center at minimum psi, and with the pump off center,
at 5000 psi
Maximum leakage with control on center:
2.0 gpm (7.6 l/m)
Minimum leakage with control on center:
1.0 gpm (3.8 l/m)
Maximum leakage with control off center:
35 cu. in/min or .15 gpm (574 cm
3
/min. or 0.57 l/m)
17. Unload pump. Stroke pump above and below center. Control should operate
smoothly. Brake pressure should drop to case pressure each time control is on center,
and it should indicate servo pressure as soon as input shaft is rotated CW or CCW
from center, per step 4 above.
18. Release control when pump is off center. Pump should return to center. Repeat
several times in each direction and at different pressures from 200 to 5000 psi (13.8 to
345 bar).
19. Remove needle valve from bypass exhaust port and install exhaust line.
20. Restore shuttle valve and system pressure settings to original operating condi-
tions.
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