Paccar Braden PD12C, Инструкция по установке, обслуживанию и ремонту

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DESCRIPTION OF HOIST
Th e hoist has four basic component parts:
1. Hoist base
2. Hydraulic motor and brake valve
3. Brake cylinder and motor support
4. Drum assembly
Th e drum assembly consists of three basic assemblies:
1. Drum with integral ring gear
2. Output planetary gear set
3. Primary planetary gear set
Th e hydraulic motor is bolted to the motor support which in
turn is bolted to the brake cylinder and the base. Th e motor
end of the drum, running on a ball bearing, is supported by
the brake cylinder. Th e other end of the drum runs on a ball
bearing on the support bolted to the base. Th e ring gear for
both planetary sets is machined into the drum’s inside sur-
face.
HOIST OPERATION
Th e hydraulic motor drives the sun gear of the primary plan-
etary gear set through the splined inner race of the overrun-
ning 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.
Th e primary planet carrier drives the output planet sun gear
which, in turn drives the output planet gears. Th e output
planet carrier is splined to the bearing support and cannot
rotate. Th erefore, as the output planet gears are driven by the
sun gear, they will drive the ring gear/drum.
DUAL BRAKE SYSTEM - DESCRIPTION
Th e dual brake system consists of a dynamic brake system
and a static brake system.
Th e dynamic brake system has two operating components:
1. Brake valve assembly
2. Hydraulic motor
Th e brake valve is basically a counterbalance valve with good
metering characteristics. It contains a check valve to allow
free fl ow of oil to the motor in the hoisting direction and a
pilot operated, spring-loaded spool valve that blocks the fl ow
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 su ffi cient pilot
pressure is applied to the end of the spool to shi ft it against
spring pressure and open a passage. A ft er the spool valve
cracks open, (300-500 psi cracking pressure) the pilot pres-
sure becomes fl ow-dependent and modulates the spool valve
opening which controls the lowering speed. Refer to fi gures
1, 2, and 3.
THEORY OF OPERATION
Th e static brake system has three operating compo-
nents:
1. Spring Applied, Multiple Friction Disc Static Brake
2. Overrunning Brake Clutch Assembly
3. Hydraulic Piston and Cylinder
Motor
Control Valve
Pump
To Tank
Brake Valve
Static Brake
Medium
Pressure
Low
Pressure
High
Pressure
Figure 1
HOISTING
Motor
Control Valve
Pump
To Tank
Brake Valve
Static Brake
Medium
Pressure
Low
Pressure
High
Pressure
Figure 2
LOWERING 1