AIR HORN 9K2689 - Caterpillar

Introduction
This test and adjust is checking the relief valve setting on the apron. The Implement relief pressure is the deference between the pump supply pressure and the implement tank return pressure.Required Tools
Illustration 1 g01623868
Table 1
Tool    Item    Part Number    Description    Qty    
B     198-4240     Digital Pressure Indicator Gp        
    B1     198-4234     Digital Indicator     1    
    B2     251-9600     Pressure Sensor Gp (0 to 68,900 kPa (0 to 10,000 psi))     2    
B3 198-4236     Adapter Cable As     2    Machine Preparation
Move the machine to a smooth, horizontal location. Move the machine away from other operating machines and away from personnel. Place the transmission direction control switch in the NEUTRAL position. Engage the parking brake. Lower the bowl to the ground. Retract the ejector cylinder and disengage the cushion hitch. Shut off the engine and turn the engine start switch to the ON position. Place chocks in front of the wheels and behind the wheels.
Perform the following steps prior to the pilot pressure diminishing. The procedure should be performed no more than 1/2 hour after the engine has been shut off.
Move the control levers through the full range of travel. This movement of the levers will relieve any pressure that may be present in the hydraulic system. Turn the engine start switch to the OFF position.
Slowly loosen the filler cap for the hydraulic oil tank in order to release the pressure.
Illustration 2 g02621689
View of the top and rear of the implement control valve. (1) Head end pressure relief valve (2) Rod end pressure test port (3) Rod end pressure relief valve (4) Pilot pressure relief valve (5) Pump pressure tap (6) Load sense relief valve (7) Drain to hydraulic tank tap
Remove the dust cover from pump pressure tap (5) on the implement control valve and connect tooling (B) to the test port.
Remove the dust cover from drain to hydraulic tank tap (7) on the hydraulic tank return line and connect tooling (B) to the test port.Perform the Test
Apron Raise Relief Pressure
Connect pressure sensor to pump pressure tap (5) and drain to hydraulic tank tap (7). The relief pressure is the pressure difference between pump pressure tap (5) and drain to hydraulic tank tap (7) .
Start the