Theory Of Operation - BRADEN PD12C Series Installation Maintenance And Service Manual

DESCRIPTION OF WINCH
The winch has four basic component parts:
1. Winch base
2. Hydraulic motor and brake valve
3. Brake cylinder and motor support
4. Drum assembly
The drum assembly consists of three basic
assemblies:
1. Drum with integral ring gear
2. Output planetary gear set
3. Primary planetary gear set
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 supported 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 both planetary
sets is machined into the drum's inside surface.
WINCH 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.
Dual Brake System – Description
The dual brake system consists of a dynamic brake
system and a static brake system.
The dynamic brake system has two operating
components:
1. Brake valve assembly
2. Hydraulic motor
The brake valve is basically a counterbalance valve.
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
modulates the spool valve opening which controls
the lowering speed.

THEORY OF OPERATION

flow-dependent and
Figures 2, 3 and 4.
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
Figure 2
Motor
Static Brake
Brake Valve
Pump
Low Pressure Medium Pressure
HOISTING
Figure 3
Motor
Static Brake
Brake Valve
Pump
Low Pressure Medium Pressure
LOWERING 1
– 4 –
To Tank
Control Valve
High Pressure
To Tank
Control Valve
High Pressure