How to adjust the JCB loader valve adjustment

 This article explains how to adjust the valve adjustment on a JCB loader

 

Note: If a new regulator valve is fitted, or a valve stripped, 

 

cleaned and rebuilt, then the pressure spool should be 

 

backed off to a low pressure. This will prevent inadvertent 

 

damage to the pump.

 

Flow Regulator Spool 

 

The pressure in the pump out line (pressure test connector 

 

B) should be 20 bar (290 lbf/in2) greater than the pressure in 

 

the load sense line (pressure test connector A). If not adjust 

 

 

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the regulator flow spool as described below: 

 

1

Lower the backhoe bucket and loader shovel to rest on

the ground; stop the engine; operate the control levers

to vent residual hydraulic pressure. 

 

2

Gain access to the regulator valve assembly (mounted

on the pump). 

 

3

Remove cap C and loosen locknut D. 

 

4

Turn adjusting screw E clockwise to increase pressure

setting and anti-clockwise to decrease setting. 

 

5

Repeat pressure test as detailed previously and

establish valve is set correctly. 

 

6

Tighten locknut, refit cap

 

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How to test the flow and pressure of a JCB Loader metering pump

 This article explains how to test the flow and pressure of a JCB Loader dosing pump

 

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 Before removing the pump it is necessary to determine the

source of any problem by measuring the output flow at system pressure from 

 

both of the pump outlet ports. To check flow it is necessary to fit flow meter A 

 

 into the output line of each pump section in turn. If available, load valve B 

 

 (service tool 892/00270) should also be installed (see Note 1). Make sure the 

 

flow meter is installed with its arrow pointing away from the pump and, if 

 

applicable, located between the pump and the load valve. Note 1: If no load 

 

valve is available, ignore the references to the load valve in Fitting/Removing 

 

a Flow Meter and Load Valve below. An alternative method of determining 

 

flow is included in the Checking Flow procedures following

 

 

 

Fitting/Removing a Flow Meter and Load Valve

 

Before fitting/removing a flow meter and load valve, switchoff the machine and operate the loader/excavator controls a few times to vent system pressure.

 

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WARNING：

Hydraulic fluid at system pressure can injure you. Before

disconnecting or connecting hydraulic hoses, stop the

engine and operate the controls to release pressure

trapped in the hoses. Make sure the engine cannot be

started while the hoses are open.

WARNING：

Take care when disconnecting hydraulic hoses and

fittings as the oil will be HOT.

Fitting

1 

a

Pump section 1 - disconnect hose C from the

pump. Fit the flow meter and load valve (see Note

2) between hose C and the pump. 

 

b 

 Pump section 2 - disconnect hose D from the

pump. Fit the flow meter and load valve (see Note

2) between hose D and the pump.

 

Note 2: Make sure the load valve is in the open position, i.e.

with the adjusting knob screwed fully out, before carrying

out the Checking Flow procedure.  

Removing

Removing is the reverse of fitting.  

Checking Flow

 

1

Check the setting of the Main Relief Valve (MRV) as

described in Loader Valve, Pressure Testing. Adjust if

necessary

 

2

 a

Using a load valve - fit a flow meter and load valve,

as described in Fitting, to each pump outlet in turn.

Fit a 0-400 bar (0-6000 lbf/in2) pressure gauge to

the load valve pressure test connector.

 

 

b

If no load valve is available - fit a flow meter, as

described in Fitting, to each pump output in turn.

 

3

Start the engine and bring the hydraulics up to working

temperature 50ºC (122ºF). Set the engine speed to

2200 rpm.

 

 

 

 

4 

a

Using a load valve - adjust the load valve so that

the pressure gauge reading is just below the MRV

setting.

b

If no load valve is available - raise or lower the

loader arms until the rams are fully open or closed.

Continue to operate the raise/lower control so that

system pressure builds up. Watch the flow meter

and note its reading at the moment the MRV

operates.

5

The flow reading should be as listed in Technical

Data.