What causes fault code ASRS-FORK1 (AS/RS Fork Extension — Overtravel or Position Error)?

Fork extend/retract limit sensor failed — sensor not detecting fork position. Fork drive chain stretched or belt slipped — fork position offset from encoder reading. Load on fork shifted during extension — weight imbalance causing fork mechanism stress. Fork drive motor overloaded — mechanical resistance in fork rail due to contamination or wear. Fork intermediate (mid-stage) did not lock in position — latch mechanism failure

How do I fix fault code ASRS-FORK1?

Check fork limit sensors — extend left, extend right, and retract home — verify each triggers at correct position. Inspect fork drive chain/belt — check tension and condition. Verify fork rails are clean and lubricated — contamination causes high friction and position errors. Check fork drive motor current during extension — compare to normal baseline. Inspect fork intermediate stage latch mechanism — verify it engages and disengages cleanly. Run fork calibration cycle — extend full left and full right in manual mode to verify travel limits

AS/RS Fork Extension — Overtravel or Position Error

ASRS-FORK1

Telescoping fork or shuttle mechanism extended beyond the allowed travel limit or did not reach the correct extension position for load transfer.

high asrs piler

asrs fork telescope extension position limit sensor

Probable Causes (ranked)

Fork extend/retract limit sensor failed — sensor not detecting fork position
Fork drive chain stretched or belt slipped — fork position offset from encoder reading
Load on fork shifted during extension — weight imbalance causing fork mechanism stress
Fork drive motor overloaded — mechanical resistance in fork rail due to contamination or wear
Fork intermediate (mid-stage) did not lock in position — latch mechanism failure

Fix Steps

1 Check fork limit sensors — extend left, extend right, and retract home — verify each triggers at correct position
2 Inspect fork drive chain/belt — check tension and condition
3 Verify fork rails are clean and lubricated — contamination causes high friction and position errors
4 Check fork drive motor current during extension — compare to normal baseline
5 Inspect fork intermediate stage latch mechanism — verify it engages and disengages cleanly
6 Run fork calibration cycle — extend full left and full right in manual mode to verify travel limits

Field Trick

Fork telescoping mechanisms need their rails cleaned and lubricated every 3 months. If you wait until the fork stops extending, the rails are scored and need machining. A 15-minute cleaning with a rag and light oil prevents a $15,000 fork overhaul.

Suggested Replacement Parts

Parts matched to fault category: Limit Switch

Allen-Bradley 802T-AP Limit Switch P/N: 802T-AP NEMA Type 4, lever type, 1 N.O. + 1 N.C., plug-in

AutomationDirect $65.00 Amazon $55.00 Grainger $82.00

Omron D4N-4132 Safety Limit Switch P/N: D4N-4132 Top plunger, 1 N.C. + 1 N.O., M20 conduit entry

AutomationDirect $28.00 Amazon $22.00

Prices are estimates. Verify part numbers match your equipment before ordering.

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