THEORY OF OPERATION
DESCRIPTION OF HOIST
The hoist has four basic component parts:
1. Hoist base
2. Hydraulic motor group
3. Brake cylinder and motor adapter
4. Cable drum with gear train
The hydraulic motor is bolted to the motor support which
in turn is bolted to the brake cylinder and the base. The
motor end of the drum, running on a ball bearing, is sup-
ported by the brake cylinder. The other end of the drum
runs on a ball bearing on the support bolted to the base.
The ring gear for the planetary gear train is machined into
the drum’s inside surface.
HOIST OPERATION
The hydraulic motor drives the sun gear of the primary
planetary gear set through the splined inner race of the
brake clutch. When driven by the sun gear, the primary
planet gears walk around the ring gear in the drum and
drive the primary planet carrier.
The primary planet carrier drives the output planet sun
gear which, in turn drives the output planet gears. The
output planet carrier is splined to the bearing support and
cannot rotate. Therefore, as the output planet gears are
driven by the sun gear, they will drive the ring gear/drum.
NOTE
:
The special order 07 (7:1) gear ratio has only one
planetary gear set
Dual Brake System – Description
The dual brake system consists of a dynamic brake sys-
tem and a static brake system.
The dynamic brake system has two operating compo-
nents:
1. Brake valve assembly
2. Hydraulic motor
The brake valve is basically a counterbalance valve with
improved metering. It contains a check valve to allow free
flow of oil to the motor in the hoisting direction and a pilot
operated, spring-loaded spool valve that blocks the flow of
oil out of the motor when the control valve is placed in
neutral. When the control valve is placed in the lowering
position, the spool valve remains closed until sufficient
pilot pressure is applied to the end of the spool to shift it
against spring pressure and open a passage. After the
spool valve cracks open, the pilot pressure becomes flow-
dependent and modulates the spool valve opening which
controls the lowering speed.
The static brake system has three operating components:
1. Spring Applied, Multiple Friction Disc Static Brake
2. Brake Clutch Assembly
3. Hydraulic Piston and Cylinder
NOTE
:
Some special order models have a solid hub for
brake effective both directions.
The static brake is released by the brake valve pilot pres-
sure at a pressure lower than that required to open the
pilot operated spool valve. This sequence assures that
dynamic braking takes place in the brake valve and that
little, if any, heat is absorbed by the friction brake.
6
Winch Brake
Brake
Valve
Pump
Control
Valve
Winch Assembly
W/Brake Valve
& Static Brake
DR
BR
HYDRAULIC CIRCUIT
PUMP
CONTROL
VALVE
Motor
Winch
Brake
Motor Code 010, 011, 012, 013
Motor Code 020, 029, & 039
Summary of Contents for BRADEN Gearmatic BG6A
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