205 AND 211 TRACK-TYPE EXCAVATORS Boom Lowering Speed Control Valve Caterpillar


Boom Lowering Speed Control Valve
`
1.1. Functional Description
2.1. Installation
3.1. Location of Boom Lowering Speed Control Valve

Boom Lowering Speed Control Valve - Fig. WH 221

(1) Housing

(2) Ball

(3) Spindle

(4) Stop disc

(5) Sealing cone (check valve)

(6) Compression spring

(7) Rotary knob

(8) Seal ring

(9) Compression spring

(10) Restriction plunger

(A) Oil from left hand valve bank

(B) Oil from right hand valve bank (compound circuit)

(C) Oil toward piston head of boom cylinders

Functional Description

The boom lowering speed control valve is a combination of an adjustable restrictor valve, a check valve, a shutoff valve and check valve for the compound circuit.

The pressure oil is throttled in one direction, more or less, depending on the position of the rotary knob (7).

The oil flow (C) thereby goes to the rear side of the seal ring (8) and flows back to the left hand valve bank, through the restriction plunger.

In the opposite direction, the oil flow (B) acts upon the front face of the seal ring (8) through the check valve (5, 6), while the oil flow (A) is applied directly to the front face of seal ring (8). This is lifted from its seat and the oil flows unthrottled through the valve into the boom cylinders.

By rotating the ball (2) by means of the spindle (3), the oil flow (C) can be shut off.

Installation

The valve is mounted into the pressure oil line on the piston side of the boom cylinder.

Make sure the mounting direction is correct. The compressed oil must flow to the cylinder unthrottled, while the discharged oil flows back through the adjustable restrictor.

Installation of the restrictor check valve is to avoid that the cylinder, due to the load, is retracted faster than the oil flowing in on the opposite side can refill the cylinder chamber.

When retracting the boom cylinders, the check valve (5, 6) allows the return oil to flow back only through the left hand valve bank (secondary protection).

Location of Boom Lowering Speed Control Valve


NOTICE

Do not close the control valve too far, because there will be a possibility of overheating the hydraulic oil and causing damage to the system.


Information System:

205 AND 211 TRACK-TYPE EXCAVATORS Flexible Coupling
205 AND 211 TRACK-TYPE EXCAVATORS Towing
205 AND 211 TRACK-TYPE EXCAVATORS Control Valve Bank, Optional Actuators
205 AND 211 TRACK-TYPE EXCAVATORS Basic Cooling Block (Diverter Valve)
205 AND 211 TRACK-TYPE EXCAVATORS Check and Relief Valve (For Boom Cylinder Protection)
205 AND 211 TRACK-TYPE EXCAVATORS Hydraulic Hammer (With Stroke Frequency Adjustment)
205 AND 211 TRACK-TYPE EXCAVATORS Pump Delivery Diagrams
205 AND 211 TRACK-TYPE EXCAVATORS Variable Double Pump
205 AND 211 TRACK-TYPE EXCAVATORS Pilot-Operated Main Relief Valve
205 AND 211 TRACK-TYPE EXCAVATORS Instructions For Testing And Adjusting Hydraulic Pressure
205 AND 211 TRACK-TYPE EXCAVATORS Hydraulic System
205 AND 211 TRACK-TYPE EXCAVATORS Technical Data For Wiring Diagram
205 AND 211 TRACK-TYPE EXCAVATORS Restrictor Check Valve (Stick Cylinder)
205 AND 211 TRACK-TYPE EXCAVATORS Overload Warning Device
205 AND 211 TRACK-TYPE EXCAVATORS Hydraulic Swivel (5-way and 2-way)
205 AND 211 TRACK-TYPE EXCAVATORS Swing Bearing
205 AND 211 TRACK-TYPE EXCAVATORS Swing Gear Brake
205 AND 211 TRACK-TYPE EXCAVATORS Final Drive With Hydraulic Motor
205 AND 211 TRACK-TYPE EXCAVATORS Fault Diagnosis
6C197 And 6C198 Hydraulic Hammer Installation Arrangements{5450}
CAT QUICK COUPLER FOR CATERPILLAR & CO Using the manual
CAT QUICK COUPLER FOR CATERPILLAR & CO Attachment mounting procedure
CAT QUICK COUPLER FOR CATERPILLAR & CO Attachment release procedure
HYDRAULIC BROOM FOR CATERPILLAR BACK Safety