Worn Bore in the Hydraulic Pump Regulator Block May Cause Inadvertant Implement Movement Even When the Hydraulic Lock Lever Is in the Locked-out Position

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Worn Bore in the Hydraulic Pump Regulator Block May Cause Inadvertant Implement Movement Even When the Hydraulic Lock Lever Is in the Locked-out Position

CONFIDENTIAL

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TECHNICAL INFORMATION BULLETIN	FEBRUARY 07, 2001
EXCAVATORS	307B (5CW, 6KZ, AFB) EXCAVATORS
	Component Code(s) 5070

SUBJECT: WORN BORE IN THE HYDRAULIC PUMP REGULATOR BLOCK MAY CAUSE
INADVERTANT IMPLEMENT MOVEMENT EVEN WHEN THE HYDRAULIC
LOCK LEVER IS IN THE LOCKED-OUT POSITION

PROBLEM:

An internal oil leak in the pump regulator may occur due to a worn bore in the 150-5921 Regulator Block. The leak will cause pilot pressure to build in the down stream circuit. If the joystick is slightly moved, pressure can build up and activate a main valve spool, even with the safety lever in the lock position.

SOLUTION:

If this problem is encountered in the field, cancellation of the positive control circuit is required. Refer to the procedure that follows:

CANCELLING THE POSITIVE CONTROL CIRCUIT

This procedure outlines the steps to cancel the positive control circuit and increase the response of the main pump flow control. Note that this action results in loss of smooth control. The controllability will be similar to that of a 307 Excavator.

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REQUIRED PARTS
ITEM	PART NO.	DESCRIPTION	QTY.
1	030-7947	Elbow	1
2	3J-1907	Seal	5
3	6V-9508	Plug	1
4	6V-8397	Seal	1
5	2P-1314	Connector	1
6	9S-4191	Plug	2
7	6K-9194	Elbow	1
8	030-7955	Tee	1
9	052-0572	Tee	1
10	8T-0398	Reducer	1

February 07, 2001
Component Code 5070

Procure the required parts listed in the table.
Disconnect the 108-7153 Hose Assembly (M) between pump port (B) and port (Q) in pressure reducing valve (R).
Disconnect the 4I-1422 Hose Assembly (A) between pump port (C) and port (P) in pressure reducing valve (R). Connect port (Q) in pressure reducing valve (R) with 6K-9194 Elbow (7) and 030-7955 Tee (8).
Disconnect the 4I-7678 Hose Assembly (L) between port (G) in manifold (J) and pressure reducing valve (R). Reconnect to pump port (B).
Disconnect the hose between pump port (F) and positive control signal (D). Block the positive control signal with 6V-9508 Plug (3) and 6V8397 Seal (4).
Disconnect the 108-7288 Hose Assembly (K) between port (H) in manifold (J) and pressure reducing valve (R) to assemble 8T-0398 Reducer (10) and 052-0572 Tee (9) in between.
Connect the 108-7153 Hose Assembly (M) between pump port (F) and pressure reducing valve (R) by using the 2P-1314 Connector (5). Connect the routing between pump port (F) and pressure reducing valve (R).
Block pressure reducing valve (R) ports (N) and (P) with 9S-4191 Plugs (6) and 3J-1907 Seals (2).

Illustration 1 shows the hydraulic schematic with the positive control circuit enabled. Illustration 2 shows the hydraulic schematic with the positive control circuit cancelled. Illustration 3 shows an assembly drawing of the hydraulic components with the positive control circuit cancelled.

February 07, 2001
Component Code 5070

Illustration 1. Current configuration with the positive control circuit enabled.

Illustration 2. Configuration with the positive control circuit cancelled.

February 07, 2001
Component Code 5070

Illustration 3. Component assembly for cancelling the positive control circuit.

(A). 4I-1422 Hose Assembly
(B). Pump Port (Pp)
(C). Pump Port (Ps)
(D). Positive Control Signal
(E). Pump
(F). Pump Port (Pz)
(G). Manifold Port (PIN)
(H). Manifold Port (DR3)
(J). Manifold
(K). 108-7288 Hose Assembly
(L). 4I-7678 Hose Assembly
(M). 108-7153 Hose Assembly
(N). Pressure Reducing Valve Port (P)
(P). Pressure Reducing Valve Port (A)
(Q). Pressure Reducing Valve Port (T)
(R). Pressure Reducing Valve