8
THEORY OF OPERATION
HOIST
LOWER
OPERATION OF DUAL BRAKE SYSTEM
Because the static brake on this winch is effective both di
-
rections, the brake must be hydraulically released to operate
the winch in either the hoist or lower direction.
This also means cable can be wound onto the drum in either
direction without any modifications to the winch.
When the winch is powered in either direction, the motor
cannot rotate until sufficient pilot pressure is present to open
the correct counterbalance cartridge. The friction brake
will completely release at a pressure lower than required
to open the counterbalance cartridge. The extent to which
the cartridge opens will determine the amount of oil that can
flow through it and the speed at which the cable drum will
turn. Increasing the flow of oil to the winch motor will cause
the pressure to increase and the opening in the cartridge to
enlarge, speeding up the cable drum. Decreasing this flow
causes the pressure to drop and the opening in the cartridge
to decrease, slowing down the cable drum.
When the control valve is returned to the neutral or center
position, pressure will rapidly drop and the counterbalance
cartridge will close, stopping the load. The friction brake will
engage and hold the load after the cartridge is closed.
