Testing And Adjusting

Usage:

Hydraulic System

Introduction

NOTE: For Specifications with illustrations, make reference to the HYDRAULIC SPECIFICATIONS for 153 & 163 HYDRAULIC CONTROL, Form No. REG01693. If the Specifications given in Form REG01693 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications in the book with the latest date.

When making a check of the hydraulic system, do the visual checks and measurements first. Then do the operational checks and then the instrumentation checks.

Use the 5S5123 Hydraulic Testing Group, a stop watch, a magnet and an inch (mm) scale for basic test to measure:

1. The pressure setting of the relief valve. A low pressure setting will lower the performance of the machine. A too high pressure setting will cause a reduction in the life of hoses and other parts of the system.

2. Lift, tilt, and ripper circuit drift rates. Circuit drift is caused by leakage past cylinder piston seals, control valve seals, check or make-up valves and/or too much spool to valve body clearance.

3. Dozer lift and tilt cycle times. Too much cycle time is caused by leakage, pump wear and/or pump speed.

To make an adjustment to parts in the tank, it is necessary to remove the tank from the machine.

The two and three-valve systems have a modified series circuit arrangement. The hydraulic pump and the pressure relief valve are common to all circuits. Each circuit has a check valve to prevent cylinder drift when the valve spool is first moved. The lift circuit also has a make-up valve (anti-cavitation) to add tank oil to the pump flow when the dozer blade lowers faster than the pump can supply oil to the head ends of the cylinders.

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When testing and adjusting the hydraulic system, move the machine to a location in dirt, not rock or concrete. Move away from job traffic and away from personnel. Allow only one man on the machine. Keep all other personnel off to one side and in view of the operator.

Visual Checks

A visual check of the system with the engine stopped is the first step when troubleshooting a problem. With the blade lowered to the ground, make the following checks:

1. Make a check of the oil level. Slowly loosen the tank filler cap. If oil comes out the bleed hole when the filler cap is loosened, let the tank pressure bleed off before removing the filler cap.

2. Remove the filter elements. Look for materials on the elements. A magnet will separate ferrous metal material from non-ferrous metal and non-metalic sealing material (piston rings, O-ring seals, etc.).

3. Look at all lines, connections and cylinders for damage or leaks.

Checking Pump Efficiency

For any pump test, the pump flow, measured in gpm (lit/min) at 100 psi (7.0 kg/cm²) will be larger than the pump flow at 1000 psi (70.3 kg/cm²) at the same rpm.

The difference between the pump flow of two operating pressures is the flow loss.

Method of finding flow loss ...

Flow loss when expressed as a percent of flow loss is used as a measure of pump performance.

Example of finding percent of flow loss ...

If the percent of flow loss for a gear type pump is more than 10% on the machine (15% on the bench test), pump performance is not good enough.

^*Numbers in examples are for illustration and are not values for any specific pump or pump condition. See HYDRAULIC SPECIFICATIONS FOR 153 & 163 HYDRAULIC CONTROLS, Form No. REG01693, for pump flow of a new pump at 100 psi and 1000 psi.

Test On The Machine

Install a 9S2000 Flow Meter. Measure pump flow at 100 psi (7.0 kg/cm²) and at 1000 psi (70.3 kg/cm²) with engine at 2000 rpm.

NOTE: See Test Tooling Chart, Form Number REG00910.

Formula I:

Test on the Bench

If the test bench can not be run at 1000 psi at a high rpm, do the first part of the test with the pump shaft rotation at half speed of the pump. See HYDRAULIC SPECIFICATIONS FOR 153 & 163 HYDRAULIC CONTROLS, Form No. REG01693, for HALF SPEED data for pump being tested. Measure pump flow at 100 psi (7.0 kg/cm²) at 1000 psi (70.3 kg/cm²). Then in order to measure the pump flow for the last part of the test, see SPECIFICATIONS for: Pump rpm at 100 psi with the engine at FULL SPEED rpm.

Formula II:

Operation Checks

The operational check of the system is used to make a diagnosis of inside leakage, bad valves or pump.

Raise and lower the blade several times.

1. Look at cylinder extension and retraction for erratic movement (not a smooth movement).

2. Make a check for pump being noisy.

3. Look for relief valve action. The relief valve must not open except when an external force causes system pressures to become too high.

When or if hydraulic circuit inside leakage is the problem, make the pressure checks first. If operation is still slow, use a 9S2000 Flow Meter to find the leakage. A test of the hydraulic pump is made by using the instruments in the PUMP TEST PROCEDURE-I, Form REG01165.

Hydraulic System Test Procedures

Pump

Make a check of the relief valve pressure seeting. See TESTING THE PRESSURE RELIEF VALVE. Make a check of the setting with the engine running at low idle. If the pressure setting is correct at low idle, the output of the pump is good.

If the machine has a tilt and/or ripper circuit, make a connection into these circuits. Make a check to see if relief valve setting is correct at low idle. If the pressure is not correct in all circuits, the condition of the pump or relief valve is probably good. If the pressure is low in only one circuit, the pump and/or relief valve is bad. If the pressure is low in only one circuit, see the drift tests for that circuit for more testing.

Lift Circuit Drift Test

TEST NO. 1: Raise the front of the machine off the ground by lowering a level blade. Put the control lever in HOLD position. Shut off the engine and see if the lift cylinder rods move into the cylinders.

TEST NO. 2: Raise the front of the machine off the ground by lowering a level blade. Shut off the engine. Hold the lift control lever in LOWER position and see if the lift cylinder rods move into the cylinders.

TEST NO. 3: Raise the blade off the ground. Put the control lever in HOLD position. Shut off the engine and see if the lift cylinder rods move out of the cylinders.

TEST NO. 4: Raise the blade off the ground. Shut off the engine. Hold the lift control lever in RAISE position and see if the lift cylinder rods move out of the cylinders.

Tilt Circuit Drift Test

TEST NO. 1: Put the cutting edge of the blade flat on the ground. Raise the front of the machine off the ground by lowering the right side of the blade (TILT RIGHT). Put the tilt circuit in HOLD position. Shut off engine and observe if the tilt cylinder rod moves into the cylinder.

TEST NO. 2: Put the cutting edge of the blade flat on the ground. Raise the front of the machine off the ground by lowering the right side of the blade (TILT RIGHT). Shut off the engine. Push on the right tilt pedal (TILT RIGHT). See if the tilt cylinder rod moves into the cylinder.

TEST NO. 3: Put the cutting edge of the blade flat on the ground. Raise the front of the machine off the ground by lowering the left side of the blade (TILT LEFT). Put the tilt circuit in HOLD position. Shut off the engine and see if the tilt cylinder rod moves out of the cylinder.

TEST NO. 4: Put the cutting edge of the blade flat on the ground. Raise the front of the machine off the ground by lowering the left side of the blade (TILT LEFT). Shut off the engine. Push the left tilt pedal (TILT LEFT). See if tilt cylinder rod moves out of the cylinder.

Ripper Circuit Drift Test

TEST NO. 1: Raise the rear of the machine off the ground by lowering the ripper. Put the ripper control lever in HOLD position. Shut off the engine. See if the ripper cylinder rod moves into the cylinder.

TEST NO. 2: Raise the rear of the machine off the ground by lowering the ripper. Shut off the engine. Hold the ripper control lever in LOWER position. See if the ripper cylinder rod moves into the cylinder.

TEST NO. 3: Raise the ripper off the ground. Place the control lever in HOLD position. Shut off the engine. See if the ripper cylinder rod moves out of the cylinder.

TEST NO. 4: Raise the ripper off the ground. Shut off the engine. Hold the ripper control lever in RAISE position. See if the ripper cylinder rod moves out of the cylinder.

Testing The Pressure Relief Valve

The pressure relief valve can be tested on the machine with the 5S5123 Hydraulic Testing Group or it can be removed and tested on a hydraulic test bench. The oil must be at normal operating temperature.

The pressure at which the relief valve opens must be checked and, if needed, an adjustment made to get the correct opening pressure.

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NOTICE

Use only high pressure testing equipment; pressure can be more than 2275 psi (160.0 kg/cm²).

Before installing the test equipment, place the cutting edge of the blade flat on the ground. Lower the ripper, if so equipped, to the ground. With the engine off, move all hydraulic control levers to all positions to let the pressure out of the hydraulic lines. Put the control levers in the HOLD position.

If the machine is equipped with a ripper or tilt circuit, the relief valve can be checked in either of these circuits using the correct pressure plate assembly. The cover (1) is not used. The cylinder rods are moved in or out until the piston contacts the end of the cylinder.

The following procedure is for testing the pressure relief valve when the machine is equipped with a lift circuit only.

The 5H4020 Cover (1) and O-ring seal is used to block the oil in the head ends of the cylinders. A check of the relief valve can not be made by moving the pistons to the ends of the cylinders. The pistons have valves which open and let oil go to the tank when the pistons contact the end of the cylinders.

BLOCKING PLATE INSTALLED
1. 5H4020 Cover and O-ring seal. (Installed in head end of left lift cylinder).

Disconnect the lines (3) and (4). Insert a 5H4040 Cover and O-ring seal (1) in the rod end line. Install test equipment (2) in the head end of line.

TESTING PRESSURE RELIEF VALVE
1. 5H4020 Cover and O-ring seal. 2. Test equipment: 5S4648 Hose Assembly, 4M5317 Bushing, 1S8937 Valve, 1S8936 Gauge (0-4000 psi) and a 5S4967 Pressure Plate Assembly. 3. Head and line. 4. Rod end line.

Start the engine. Pull the lift control lever slowly to raise the blade. Hold the control lever in RAISE position and increase the engine speed to HIGH IDLE. The pressure reading on the gauge must be 2250 ± 24 psi (158 ± 1.7 kg/cm²). If the pressure is not correct, stop the engine and remove the tank. Remove the tank cover. Loosen locknut (5) and turn screw (6) clockwise to raise the pressure setting of the relief valve. Turn the screw (6) counterclockwise to lower the pressure setting. Tighten locknut (5) to 18 ± 5 lb. ft. (2.5 ± 0.5 mkg).

ADJUSTING PRESSURE RELIEF VALVE (Single Valve Tank)
5. Locknut. 6. Screw.