OP-755 Part 2 Pages 197-401 - Personal Page of GENE SLOVER

• (f)
201
direction from center reverses the direction
of flow and the direction of B-end rotation.
(e) Safety relief valves are high pressure relief
valves functioning to relieve the closed system
in the event of excessive torque or too
rapid shifting from neutral toward maximum
stroke. The valves by-pass from the high to
the low (return) pressure lead.
(d) The valve block (dr. 271698) is a housing for
the control circuit valves and fluid passages.
It is supplied by fluid displaced by the auxiliary
purup . TDe following valves are located
in the block.
Starting valve
Control valve
Interlock valve
Hydraulic motor by-pass
Auxiliary pump relief valve
Main circuit replenishing checks
(e) The starting Camcontour controls the displacement
movement of the spring loaded starting
valve. The valve is shifted to operating position
when the control lever is shifted from
neutral and with the valve thus set the valve
vents are closed, the interlock valve is vented
to the tank and is shifted to starting posi
tion. Whenthe cam movesthe starting valve
to "s top" position, the brake cylinder, the
control valve piston, and the by-pass valve
operating line, are vented to the tank. Simultaneously
the interlock valve is reset and
held in starting position by pressure .
The control valve cam guides the latch of the
control valve. The latter is spring loaded
to require the latch to follow the camcontour
(except as cited below). The control valve
is a three piece unit comprising a piston,
plunger and valve. It has three-position
movement: To start, run and stop. In the
starting position the spring is relieved and
the piston is held by pressure only. B-end