Hydraulic System - JUNTTAN PM 20L Operator's Manual

Table of Contents

Advertisement

JUNTTAN
Routine service section
7.4

HYDRAULIC SYSTEM

The hydraulic system of Junttan rig is an open design and consists of 3 axial piston
pumps, which are mounted directly with a clutch and transmission at the flywheel end
of the engine. The displacement of main pumps can be adjusted and they have a power
regulation. The displacement of third pump is constant. There is also a small double
gear-type pump in the accessory drive of the engine.
The oil is sucked from the hydraulic tank into the pumps. From the first part of double
pump the oil goes to valve block A, from the second part to valve block B and from the
third pump to valve block E. On each valve block there are main relief valves and
pressure relief valves for different functions. For some functions there are also flow
restrictors on the valve block. The valves in the valve blocks are operated with electric
or hydraulic pilot valves. Some of the hydraulic circuits have hydraulic accumulators to
reduce the pressure surges.
The oil flow from the pumps to the hammer goes thru blocks. Depending on oil amount
the hammer needs, the main pumps or all three pumps are connected to the hammer.
The valves on the blocks have to be in the neutral position, so that the hammer can use
all oil.
In the cab there are gauges to indicate the pressures of the main circuits. Additionally
there are quick-release couplings in the hydraulic compartment for each of the pumps
for connecting a separate pressure gauge. There are pressure and return filters in the
system. After passing through the hydraulic motors, cylinders etc. the oil goes to the
collection sump. The main part of the oil goes thru the oil coolers to the tank.
During the piling, when piling mode switch is in position 1 or 2, the oil is piloted to
hammer circuit and relieve valve regulates the pressure in the circuit. The unloading
valve is closed. When the piling mode switch is turned to position 0, the unloading
valve opens and pilotes the hammer circuit pressure to the tank line. The pilot valves get
the pressure from the hydraulic pumps. The pilot pressure is 35 bar. Depending on the
type the winches have a separate drain line equipped with a filter (BB- and 500A-
winches). The pressure of collection sump is used in some winch models (BB- and
500A-winches) to build winch case pressure and in some models (500A-winches) also
to pre-heating.
Oil coolers
E
A
B
109

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the PM 20L and is the answer not in the manual?

Table of Contents

Save PDF