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Circle Timing

This document provides instructions for checking and adjusting the circle timing on a machine. It is a 3-step process: [1] Ensuring correct drive pinion clearance and cylinder positioning, [2] Checking that the spool hole is visible and centered in the port, [3] If not centered, loosening a lock nut, adjusting a pinion shaft until the spool is centered, and retightening the lock nut. The instructions include 8 steps to adjust the spool if needed and ensure proper circle rotation after adjustment.

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2K views3 pages

Circle Timing

This document provides instructions for checking and adjusting the circle timing on a machine. It is a 3-step process: [1] Ensuring correct drive pinion clearance and cylinder positioning, [2] Checking that the spool hole is visible and centered in the port, [3] If not centered, loosening a lock nut, adjusting a pinion shaft until the spool is centered, and retightening the lock nut. The instructions include 8 steps to adjust the spool if needed and ensure proper circle rotation after adjustment.

Uploaded by

Eldridge
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Circle Timing

Valid for serial numbers

Model Production site Serial number Serial number


start stop

G940 Volvo

Op nbr 912-109

Total procedure time (hr): 0.40

1.Whenever the circle turn valve has been removed, make a circle timing check. Two of the three steps
in the circle timing procedure have been performed by ensuring correct drive pinion clearance and
positioning the circle turn cylinders and cranks. The third step in the sequence is adjusting the spool (5).
To start, disconnect the hose at the forward left port on the circle turn valve. Immediately cap the hose
end to prevent contamination. Remove the fitting.

Risk of personal injury! Wear safety glasses and use protective gloves.

Figure 1

2.Look inside the open port. A hole on the spool (5) should be visible and it must be in the center of the
port. If so, the spool is in the proper position. Connect the hose.
Figure 2

3.If the hole in the spool is not visible or it is not in the center of the port, the spool (5) needs
adjustment.

Figure 3

4.To adjust the spool (5), first loosen the lock nut (12) retaining the valve pinion (14).

Figure 4

5.Turn the pinion shaft (16) until the hole on the spool (5) is visible and is in the center of the port. Move
the spool back and forth until the edges are visible. Now centralize the spool.
Figure 5

6.Tighten the lock nut (12). Check the position of the spool (5) and make sure that it has not moved
when tightening the lock nut. Install the fitting and connect the hose.

Figure 6

7.Make a visual check around the machine. Signal the intention to start the engine. Start the engine
when it is safe to do so and push the circle turn control lever forward. The circle should turn smoothly in
a counter clockwise direction. If the circle turns in a clockwise direction as viewed from the operator's
seat when the lever is pushed forward, the spool (5) is 180° out of position. Shut down the engine.
Repeat steps 4 through 6, but this time, turn the pinion shaft (16) 180°. Repeat step 7.

8.Refill the hydraulic oil tank to the proper level with clean lubricant. Refer to Hydraulic oil tank,
cleaning.

Circle turn valve overhaul and circle timing is now complete.

Test the machine to ensure there are no problems with the circle turn valve functions. Check all
connections for leaks.

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