631K and 637K Wheel Tractor-Scraper Systems Hydraulic Cylinder Cycle Time - Check Caterpillar

Specifications

Introduction

Prepare the machine for testing by completing the procedure that is specified in the Service Manual module Troubleshooting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

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 lever in the NEUTRAL position. Engage the parking brake. Lower the bowl to the ground. Stop the engine and place chocks in front of the wheels and behind the wheels.

Speed Tests

Perform all tests with the hydraulic oil at the normal operating temperature. Also, make the tests when the tractor engine is at high idle rpm. Use a stop watch in order to find the travel time.

If the travel time is not correct, check the following list:

• Check pump efficiency.

• Check the setting of the main relief valve.

• Check the operation of the valve spools in the control valve.

• Check the piston seals in the cylinders.

Travel Time for Lifting the Bowl

1. Start the engine and run the engine high idle.

2. Lower the scraper bowl to the ground.

3. Hold the bowl control lever in the up position. The bowl must move from the ground to the full up position in less than 3.5 ± 0.5 seconds.

   This time is based upon a stroke to the ground of 540 mm (21.3 inch).

Travel Time for the Ejector

Ejector Forward Time

1. Start the engine and run the engine at high idle. Operate the ejector.

2. Move the ejector to the rear of the scraper bowl.

3. Shift the ejector control joystick into the ejector forward position. The ejector shall move to the full forward position within 8.5 ± 0.5 seconds.

Ejector Return Time

1. Start the engine and run the engine at high idle. Operate the ejector.

2. Move the ejector to the full forward position. Shift the control joystick into the detented ejector return position

3. Shift the ejector control joystick into the ejector forward position. The ejector shall move to the full reaward position within 8.5± 0.5 seconds. When the ejector reaches the full rearward position, the joystick shall return to the NEUTRAL position.

4. The ejector kickout pressure is 18000 kPa (2610 psi)

Travel Time for the Bail (if equipped)

Lower the bail completely. The time that is needed to raise the bail is determined by shifting the solenoid valve to the BAIL RAISE position at high idle rpm. The time that is needed to lift the bail to the maximum height is 1.5 ± 0.5 seconds.

The time that is needed to lower the bail is determined by shifting the solenoid valve to the BAIL DOWN position at high idle rpm. The time that is needed to lower the bail completely is 2.1 ± 0.5 seconds.

When the cushion-hitch is on and the bail is raised completely, turn off the engine. The bail must move to the BAIL DOWN position within 33 seconds. The accumulator should be purged within this time period.

Travel Time for the Apron Lift

Start the engine and run the engine at high idle. Lower the scraper bowl to the ground and raise the apron to the FULL Raise position. The time that is needed to lift the apron to the maximum height is 4.0 ± 0.5 seconds.

Start the engine and run the engine at high idle. The time that is needed to lower the apron is 3.8 ± 0.5 seconds.

Travel Time for the Cushion Hitch Cylinder

Raise Time

1. Start the engine and run the engine at high idle.

2. Place the cushion hitch switch in the RIDE position.

3. The cushion hitch shall jump off the stop and raise to approximately 190 mm (7.5 inch) of the cylinder stroke in less than one second. The cylinder will then lower to the carry position.

   Note: Wait a minimum of two minutes between each check.

Lower Time

1. Start the engine and run the engine at high idle.

2. Place the cushion hitch switch in the LOCK DOWN position. The cushion hitch shall lower to the stop in less than nine seconds.

Dead Engine

1. Start the engine and run the engine at high idle.

2. Place the cushion hitch in the RIDE position.

3. Turn the engine OFF.

4. The cushion hitch shall lower to the stop in 15 seconds. The accumulator oil shall also purge down in 15 seconds or less.

Steering Cycle Time

1. Start the engine and operate at LOW IDLE.

2. Release the parking brake and raise the bowl.

3. Slowly steer the machine to the right into the steering stop.

4. Increase engine speed to HIGH IDLE.

5. Steer the machine from the right steering stop to the left steering stop as fast as possible. The speed of the steering should be 5.0 ± 0.5 seconds.

6. Steer the machine from the left steering stop to the right steering stop as fast as possible. The speed of the steering should be 5.0 ± 0.5 seconds.