General Machine Products 70605 Trailer Mounted Fiber Optic Puller - Manual (Page 15)

Page 15 of 24 General Machine Products Co., Inc.
6.4 RELIEF VALVE SETTING
Reference should be made to the hydraulic circuit diagram on page 19 of this manual.
There are four relief valves in the circuit and with the exception of item 10, all have been
factory pre-set and should not be adjusted. Item 10 is adjusted by the operator to set a
maximum pulling tension.
If it is necessary to replace or adjust any of the relief valves, the following guidance should
assist.
Item 7 This is a Capstan directional control valve. The relief valve is mounted in the body of
this control valve and is the main system relief valve. With a Dynamometer in the rope load
line, and with 4 complete turns around the capstan, this relief valve should be set to relieve
at 1200 lbs. (550 kg), approx. 1880 psi (130 Bar). Note: Relief valve adjustment is hidden
by a protective cap and sealing washer.
Item 8 This relief valve is situated on the drum directional control valve. This controls the
rope tension between Capstan 10 and Drum when pulling in. The valve should be set to
relieve when the rope tension measures approx. 85-110 lbs. (40-50 kg). This measurement
and adjustment should be made when the rope drum is almost empty. Note: Relief valve
adjustment is hidden by a protective cap and sealing washer.
Item 2 This relief valve is mounted in an aluminum body connected to the drum hydraulic
motor. This valve prevents drum overrun when paying out under power. With the rope drum
almost empty, the relief valve can be set so that a rope tension of approx. 85 lbs. (40 kg)
will cause the drum to rotate.
Item 10 This relief valve is mounted in an aluminum body connected to the capstan hy-
draulic motor. It is intended that the site supervisor will set this relief valve to give maximum
rope tension to suit specific operating conditions. There are two adjustments, limiting for-
ward and reverse.
Item 7 Item 8 Item 2
Item 10
(Forward Capstan)
Item 10
(Reverse Capstan)
Control Panel Front Control Panel Rear