Using 7S8896 Scraper Flushing Group For Flushing Contaminated Hydraulic Systems{0020} Caterpillar

Adaptability: All Hydraulic Tractor-Scrapers

General Information

Flushing procedures are outlined for "Gradual Failure" and "Sudden Failure". Gradual failure is a slow decline in available hydraulic power, which results from a build-up of particles in a hydraulic system caused by component wear or outside contamination. "Sudden Failure" is an instantaneous loss of hydraulic power, caused by failure of a hydraulic pump, cylinder or other component which has heavily contaminated the hydraulic system. Flushing procedure is the same for all machines unless indicated.

Gradual Failure Flushing Procedure

DISCONNECT

REMOVE

(1) Position machine with ejector forward, bowl and apron fully raised. Securely block scraper bowl and apron in raised position and shut down engine. Release hydraulic pressure on bowl lift cylinders, by momentarily shifting bowl control lever to down position, allowing scraper bowl to rest on the blocks.

(2) Drain hydraulic tank.

(3) Install new filter elements.

(4) Remove apron blocking. Remove plug (1) and allow oil to drain, then shift apron control lever to down position, allowing apron to drop slowly. When completely lowered install plug (1).

(5) Disconnect hoses (2) and (3) from apron cylinder.

(6) Connect hoses (2) and (3) together using 6J1685 Tube (4).

(7) On all machines except J-619, J-621, 633 disconnect hoses (5), (6).

(8) Loosen lower end of hose (6); rotate hose 180°. Bolt hoses (5), (6) together.

(9) On 633 disconnect hoses (7), (8).

(10) Connect hoses (7), (8) together.

(11) On J-619 and J-621 disconnect hoses (9), (10), (11), (12).

(12) Bolt hose (9) to (12) and hose (10) to (11).

(13) Loosen bolts .25" (6, 3mm) at bottom of tubes (13), on both bowl lift cylinders. Pry tube out to drain cylinders.

(14) When draining ceases, retighten bolts on tubes (13).

(15) On 630, 631, 632, 641, 650, 651 Scrapers, disconnect ejector cylinder hoses (14), (15).

(16) Connect hoses (14), (15) together using tube (4). If necessary, loosen and rotate hoses to allow clearance for tube (4).

(17) On 657, 660, 666 Scrapers disconnect hoses (16), (17).

(18) Connect hoses (16), (17) together with tube (4).

(19) On 633 Scrapers disconnect ejector hose (18) and hose (19).

(20) Connect hose (19) as shown.

(21) On J-619 and J-621 Scrapers reconnect hoses to bypass bottom door and ejector cylinders as shown.

(22) On 621 and 631 with common steering and implement circuits, disconnect hoses (20) and (21).

(23) Interconnect tubes (22) with hose (20).

(24) On cushion hitch scrapers remove plate (23) and hose (24), and disconnect hose (25). WARNING: Do not disconnect lines in cushion hitch circuit until engine has been shut down for at least five minutes.

(25) Connect hose (25) as shown.

(26) Clean and refill hydraulic tank. CAUTION: Warm up the unit until hydraulic oil is at normal operating temperature. This prevents the bypass valve from opening during flushing procedure, and insures immediate filtration after new filter elements are installed.

(27) With engine at high idle, hold control levers in the following positions for fifteen minutes each: Bowl Raise, Bowl Quick-drop, Apron Raise, Apron Lower, Eject and Eject Return. NOTW: On scrapers with two ejector cylinders, (except 633) omit eject cycle from flushing procedure. On 633, also hold control lever in Eject Fast position. On cushion hitch scrapers place in Cushion Ride and Cushion Lock-down positions. NOTE: On 621 and 631, turn the steering wheel alternately right and left (maximum travel) during the flushing procedure. CAUTION: Do not allow hydraulic oil temperature to exceed 200° F. (93.4° C.) during flushing. Cycle all bypassed cylinders manually to eject contaminated oil.

(28) Reconnect all hoses to appropriate locations on each respective cylinder following removal of added tube assemblies, hose covers and hardware. Drain hydraulic tank, install new filter elements. Refill hydraulic tank. Start engine, lower scraper bowl to ground, and move ejector 1/3 of its travel forward. Shut down engine and replenish oil in hydraulic tank. Continue to move ejector forward in 1/3 increments, each time replenish oil in hydraulic tank. Operate all hydraulic systems, bleed and replenish oil supply in hydraulic tank.

NOTE: Replace filter elements at 50 and 500 service meter hours after flushing.

Sudden Failure Flushing Procedure

(1) Position scraper with bowl and apron on the ground, and ejector to the rear.

(2) Drain hydraulic tank; remove tank cover (1).

(3) Thoroughly clean hydraulic tank and components. Install tank cover and refill hydraulic tank.

(4) Install new filter elements.

(5) Remove, disassemble and thoroughly clean all hydraulic valves and cylinders. After reassembly, cover cylinder, valve and hose openings with appropriate covers. Connect hydraulic lines following the procedure outlined in Steps 4 thru 25, under Gradual Failure Flushing Procedure.

(6) On J-619, J-621 disconnect hoses (2), (3).

(7) Connect hoses (2) and (3) together using tube (4).

(8) On 633, disconnect hoses (5), (6).

(9) Connect hoses (5), (6) together using tube (4).

(10) With engine at high idle, hold control levers in the following positions for fifteen minutes each: Bowl Raise, Bowl Quick Drop, Apron Raise, Apron Lower, Eject and Eject Return.

NOTE: (On scrapers equipped with two ejector cylinders, except for 633, omit the eject cycle from flushing procedure. On 633, also hold control lever in Eject Fast position; engage 633 Elevator in high and low positions for fifteen minutes.) On J-619 and J-621, engage elevator in high, low and reverse positions for fifteen minutes. On cushion hitch scrapers, place in Cushion Ride and Cushion Lock-down positions for fifteen minutes. On 621 and 631, turn steering wheel alternately right and left (maximum travel) for fifteen minutes.

(11) Install all cylinders, valves, hoses and tube assemblies. Reconnect all hoses to appropriate location on each cylinder following removel of added tube assemblies, hose covers and hardware. Drain hydraulic tank and install new filter elements. Refill hydraulic tank. Start engine, lower scraper bowl to ground and move ejector 1/3 of its travel forward. Shut down engine and replenish oil in tank. Continue to move ejector forward in 1/3 increments, each time replenishing oil in tank. Replace filter elements at 50 and 500 hour intervals subsequent to flushing.