Oil & Gas
Actuated pipeline and ESD valves needing fail-safe manual operation.
Declutchable · Manual Override · Actuated Valves
Declutchable manual override gearboxes let an operator drive an actuated valve by hand when power or the actuator fails. A clutch engages the handwheel and disengages it for normal automatic operation, so the override never fights the actuator. The self-locking worm holds the valve at any position, on ISO 5211 or ISO 5210 mounting.
Application Foundation
A declutchable manual override gearbox provides hand operation of an actuated valve when electric power, instrument air, or the actuator itself is unavailable. A clutch mechanism engages the handwheel to the gear train for manual operation and disengages it during normal automatic cycling, so the handwheel does not spin under power and the override does not load the actuator.
The override sits between the actuator and the valve, retaining the self-locking worm action that holds the valve at any position. Mounting follows ISO 5211 for quarter-turn valves or ISO 5210 for multi-turn gate and globe valves. Per-model torque, clutch, and dimensional specifications are confirmed per order — request a datasheet for the matched configuration.
Engineering Data
| Operation Type | Valve Travel | Mounting Standard | Typical Valve Families |
|---|---|---|---|
| Quarter-turn | 90° rotation | ISO 5211 (F05–F25) | Butterfly, ball, plug |
| Multi-turn | Many revolutions, rising stem | ISO 5210 base | Gate, globe |
| Bevel (right-angle) | Per valve (90° or multi-turn) | ISO 5211 / 5210 + bevel drive | Remote / vertical-stem valves |
| Declutchable override | Manual on actuated valves | ISO 5211 / 5210 with clutch | Any actuator-fitted valve |
General selection guidance by valve travel and mounting interface; matched Matson single-stage models (M07–M16, 200–4,400 N·m on ISO 5211) and larger two-stage units are confirmed against your valve datasheet — request a datasheet.
| ISO 5211 Flange | Typical Valve Size Band* | Common Valve Families | Matson Models Offering This Flange |
|---|---|---|---|
| F05 | Small bore | Ball, plug, small butterfly | M07 |
| F07 | Small–medium bore | Butterfly (wafer), ball, plug | M07, M10 |
| F10 | Medium bore | Butterfly, ball, plug | M07, M10, M12 |
| F12 | Medium bore | Butterfly (lug), ball, gate top-work | M12, M14 |
| F14 | Medium–large bore | Butterfly, trunnion ball, gate | M12, M14, M14A, M15 |
| F16 | Large bore | Butterfly (double flange / AWWA), ball, gate | M14, M14A, M15, M16 |
| F25 | Heavy / large bore | Large AWWA butterfly, high-pressure ball, large gate | M16 |
*Valve size band is indicative only — actual flange depends on the valve manufacturer's top-work, stem, and torque rating. Flange and Matson single-stage model data are from the Matson worm gearbox catalog (M07–M16, 200–4,400 N·m). Two-stage and electric-actuator series extend up to 160,000 N·m. Confirm the exact flange against your valve datasheet.
Per-model specifications (dimensions, weights, drive-bushing details, material grades): available on request — request a datasheet. Send your valve tag, bore, pressure class, environment class, and required output torque and our engineers return a model recommendation with the matching ISO 5211 / ISO 5210 interface.
Operation
A declutchable manual override uses a clutch to connect or disconnect the handwheel from the gear train. In normal operation the clutch is disengaged, so the actuator drives the valve and the handwheel stays still. When the actuator or its power supply fails, the operator engages the clutch — usually by a lever or by pushing and turning the handwheel — to drive the valve manually through the self-locking worm.
Because the worm output is self-locking, the valve holds at any position the operator sets during manual operation. Once power is restored, disengaging the clutch returns control to the actuator. The override is sized to the valve break-to-open torque and matched to the actuator and valve mounting, ISO 5211 for quarter-turn or ISO 5210 for multi-turn.
Engineering
By Industry
Actuated pipeline and ESD valves needing fail-safe manual operation.
Automated isolation valves requiring hand backup on power loss.
Actuated process valves with manual override for outages.
Motorised valve banks needing local manual intervention.
Common Questions
A manual override gearbox is a gear unit fitted between a valve actuator and the valve that lets an operator drive the valve by hand when power or the actuator fails. A declutchable version uses a clutch to engage the handwheel only when needed, so it does not load the actuator during normal automatic operation, and the self-locking worm holds the valve position.
Engage the override's clutch — typically with a lever, or by pushing and turning the handwheel — to connect the handwheel to the gear train, then turn the handwheel to drive the valve. The self-locking worm holds the valve at any position you set. When power returns, disengage the clutch to hand control back to the actuator.
A fixed handwheel is permanently connected and spins whenever the actuator runs, which is a hazard on powered valves. A declutchable override stays disconnected during automatic operation and is engaged by a clutch only for manual intervention, so the handwheel is safe during actuator cycling and does not fight the actuator.
Yes. Declutchable overrides are matched to the valve's ISO 5211 or ISO 5210 mounting, the stem bore, and the actuator torque, so they can be specified for new or retrofit actuated valves. Provide the valve type, stem data, actuator details, and required torque, and our engineers confirm a matched configuration.
Yes. The override's worm output is self-locking, so the valve holds at any position the operator sets during manual operation, with no separate brake. This keeps the valve secure while power is restored, after which disengaging the clutch returns automatic control to the actuator.
Send your valve type, stem data, actuator details, and required torque. We match a declutchable manual override with the correct clutch and ISO 5211 / 5210 mounting, with per-model specifications on request.