Boom Elevating System

Contents

E-1 Elevating System.............................1

1. General..................................................... 1

E-2 Elevating Cylinder............................3

1. Structure...................................................3

E-3 Counterbalance Valve (Elevating)..5

1. Structure...................................................5

2. Function....................................................7

2.1 When control valve is at the neutral position.................................................7

2.2 While actuator is being pushed up.............7

2.3 While actuator descends............................7

E-1 Elevating System

1. General

Hydraulic Circuit for Boom Elevating

Elevating System

Remote Control Pressure Vent

The remote control valve and the solenoid control relief valve are connected to the hydraulic pilot control valve at the two points having the same symbols such as "a5" and "b5".

1. The boom elevating operation is controlled by the hydraulic pilot method. The pilot pressure from either the remote control valve (lever) controls the hydraulic pilot control valve.

2. The maximum pressure in the elevating hydraulic circuit is regulated by the relief valve (elevating, telescoping). The maximum pressure in the boom lowering circuit is regulated by the overload relief valve activated at low pressure to prevent the boom from hunting.

3. Circuit for boom elevating slow stop

The boom raising proportional control valve and the boom lowering proportional control valve make the boom elevating movement stop slowly. These valves control the boom elevating operation according to the output from the AML.

4. Circuit for remote control pressure vent

In this hydraulic circuit, the Hydraulic valve (pilot pressure) controls the pilot pressure to the remote control valve for boom elevating control lever.

Elevating Cylinder

E-2 Elevating Cylinder [NOTICE]

There is a case that the appearance and so on differ from the parts for this machine. Although there is not so much difference in functions and disassembly procedures, make sure of the serial number of this machine and the part sales unit described in the parts catalog before starting disassembling operations.

1. Structure

10.Cylinder

13.O-ring

Elevating Cylinder

15.Packing

*1:Face the notch or the lip toward the pressure side.

*2:Apply Three-bond 1401 or equivalent.

Thread size and tightening torque

20.Counter

Counterbalance Valve (Elevating)

E-3 Counterbalance Valve (Elevating)

[NOTICE]

There is a case that the appearance and so on differ from the parts for this machine. Although there is not so much difference in functions and disassembly procedures, make sure of the serial number of this machine and the part sales unit described in the parts catalog before starting disassembling operations.

Counterbalance Valve (Elevating)

Thread size and tightening torque

This counterbalance valve prevents the actuator from being driven by the load and its own weight faster than the speed corresponding to the oil supply rate.

2.1 When control valve is at the neutral position

The actuator holding pressure is sealed by seat “a” of the main spool and seat “b” of the check valve.

2.2 While actuator is being pushed up

1. The pressurized oil entering through port A of the control valve enters chamber C, flows out through port B by opening the check valve, and enters the holding side of the actuator.

2. At this time, since port PP is connected to the tank circuit, the main spool is kept forced to the valve body by the spring, and remains inactive.

2.3 While actuator descends

1. The hydraulic oil directly flowing from the control valve to the actuator also enters through port PP to exert force to the main spool to move the main spool.

2. Consequently, the holding hydraulic pressure in port B is vented to port A.

3. At this time, the main spool motion is smoothened by orifices.

Contents

F-1 Winch System..................................1

1. General (2M2D)........................................1

2. General (1M1D)........................................3

F-2 Winch................................................5

1. Structure...................................................5

2. Reassembly..............................................7

F-3 Hydraulic Motor (Winch).................8

1. Structure...................................................8

1.1 Hydraulic moter section..............................9

1.2 Control section assy.................................10 2. Functions.................................................11 3. Disassembly...........................................12

3.1 Removing the counterbalance valve........12 3.2 Removing the oil seal case......................12 3.3 Removing the control section assy..........12 4. Reassembly............................................13 4.1 Installing the control section assy.............13 4.2 Installing the oil seal case........................13 4.3 Installing the counterbalance valve..........13