Boom Elevating System

Contents

E-1 Boom Elevating Cylinder................1

1. Structure...................................................1

E-2 Counterbalance Valve (elevating)...2

1. Structure...................................................2

2. Pressure detector for AMA........................3

Boom Elevating Cylinder

E-1 Boom Elevating Cylinder

[NOTE]

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

Note

Before installing Piston-2, apply Loctite 638 from 1st crest to 2nd crest of thread on Rod-6. Application area is shown by ※※ marks in drawing.

Before installing Rod cover-8, apply Threebond 1104 to thread portion shown by ※ mark. After installation, bend edge of Cylinder-5 at notch (one place) to prevent rotation.

Counterbalance Valve (elevating)

E-2 Counterbalance Valve (elevating)

[NOTE]

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

Counterbalance Valve (elevating)

Thread size and tightening torque

Pressure detector [NOTE]

The adjustment of pressure detector is nnecessary.

Explanation of winch system (Hook-in Specifications)

F-1 Explanation of winch system (Hook-in Specifications)

1. General [NOTICE]

The circuit diagrams in this chapter are used only for the purpose of explaining the operation principle. As there is a possibility that some portions may differ from the actual circuits, please refer to the circuit diagrams in Chapter Z when conducting service or repairs.

1.1 Electrical Circuit

1. When the hook is hoisted up too high and touches the weight of the overwinding cutout device, the buzzer will be activated and the unloading solenoid (SOL1) will be de-energizes at the same time. (Operations such as hook hoisting-up, boom extension, and boom raising will be automatically stopped.)

If the buzzer switch is set to the off position, the buzzer will not be activated.

2.While the overwinding cutout release switch is pushed, the unloading solenoid (SOL1) is energized. (Operations such as hook hoisting-up, boom extension, and boom raising will not be automatically stopped.)

3. In a hook stowing operation the unloading solenoid (SOL1) is de-energized and the low-pressure solenoid (SOL2) is energized at the same time. (The operating pressure for hook hoisting-up becomes low.)

1.2 Hydraulic Circuit

1.When the unloading solenoid (SOL1) is energized, the unloading valve works as a main relief valve. On the other hand when de-energized, the hydraulic circuit serves to automatically stop operations such as hook hoisting-up, boom extension, and boom raising. In the automatic stop condition, the vent circuit of the unloading valve is connected to the tank circuit and the unloading valve is in unloaded condition.

2. In a hook stowing operation, the vent circuit pressure of the unloading valve is controlled by the low-pressure relief valve (LRV) and the unloading valve works as a low-pressure relief valve.

Explanation of winch system (Hook-in Specifications)

Winch System

[NOTICE]

These circuit diagrams are for the ZR500-4 series (standard specifications). As some portions may differ from your machine, please refer to the circuit diagrams in Chapter Z at the same time. These circuit diagrams show the de-energized condition.

Explanation of winch system (Hook-in Specifications)

2. Principle of operation

2.1 Hoisting up

1. When the PTO is turned on: First, the contact of the power supply relay is closed. Second, DC 24V (12V) is outputted to the following relays and switch from the No.3 terminal of the power supply relay.

- No. 2 terminal of the overwinding detection relay (for SOL1)

- No.2 & 4 terminals of the overwinding detection relay (for buzzer)

- No.1 terminal of the hook stowing operation detection switch

- No.1 terminal of the overwinding cutout release switch

2. When the hook does not touch the weight of the overwinding cutout device: As the contact of the overwinding detection swich is closed, the contact of the overwinding detection relay (for buzzer) becomes open, which does not activate the buzzer. And the contact of the overwinding detection relay (for SOL1) is closed, which energizes the unloading solenoid (SOL1). In this condition the hook can be hoisted up.

Explanation of winch system (Hook-in Specifications)

Explanation of winch system (Hook-in Specifications)

2.2 Automatic stop & overwinding cutout release switch (When the overwinding cutout device is activated during a hoisting-up operation.)

1. When the PTO is turned on:

First, the contact of the power supply relay is closed.

Second, DC 24V (12V) is outputted to the following relays and switch from the No.3 terminal of the power supply relay.

- No.2 terminal of the overwinding detection relay (for SOL1)

- No.2 & 4 terminals of the overwinding detection relay (for buzzer)

- No.1 terminal of the hook stowing operation detection switch

- No.1 terminal of the overwinding cutout release switch

2. When the hook touches the weight of the overwinding cutout device:

First, the contact of the overwinding detection switch is opened.

Second, the contact of the overwinding detection relay (for buzzer) is closed, which activates the buzzer.

Third, the contact of the overwinding detection relay (for SOL1) is opened, which de-energizes the unloading solenoid (SOL1). Then hoisting-up operation of the hook will be automatically stopped.

3. While the overwinding cutout release switch is pushed, the unloading solenoid (SOL1) is energized and hoisting-up of the hook will not be automatically stopped.

Explanation of winch system (Hook-in Specifications)

Explanation of winch system (Hook-in Specifications)

2.3 Hook stowing

1. When the hook storage lever is operated, the main circuit pressure is controlled with the low-pressure relief valve,therefore the hook is stored with an appropriate wire tension.

First, the hook stowing operation detection switch is changed and the low-pressure solenoid (SOL2) is energized.

(the electrical circuit is constructed so that the unloading solenoid (SOL1) is de-energized at the same time.)

Second, the winch lever is changed to the hoisting-up position in connection with the hook stowing lever, and the directional control valve is switched over. Then the hook is hoisted up and stowed.

Hydraulic motor (Winch)

F-2 Hydraulic motor (Winch)

[NOTICE]

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

1. Structure

General View

Hydraulic motor (Winch)

2. Thread size and tightening torque

Tightening torque

Tightening is to stop without being here once from the place where a torque reached 6.9N-m after tightening stars.

F-3 Winch [NOTICE]

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

Thread size and tightening torque

2. Principle of Operation

2.1 Hoisting up

1. The torque of the winch hydraulic motor is transmitted to the winch drum through the clutch facing.

2.2 Hoisting down

1. When no load is applied to the winch, the torque of the winch hydraulic motor is transmitted to the winch drum without passing through the clutch facing.

2. When a load is applied to the winch, the winch drum tends to rotate in the hoisting-down direction by the load. If the rotational speed of the winch drum becomes higher than the supposed speed when rotated by the torque of the winch hydraulic motor, the mechanical brake will be applied to reduce the speed. Once the speed becomes lower than the supposed one, the mechanical brake will be released. In the hoisting-down operation, these two operations described above are repeated.

Left-handed quadruple-start thread when hoisting up when hoisting down