What is a manual / pneumatic declutchable valve gearbox?

A declutchable gearbox sits between a pneumatic actuator and the valve, separating manual and pneumatic operation. In normal service the actuator drives the valve through the worm gear stage; when the air supply fails or manual operation is needed, the operator disengages the pneumatic side and drives the valve by handwheel, so the SD can take over during an emergency.

How do I select an SD model by output torque and actuator connection?

Select the model whose rated output torque meets the valve's required torque with an adequate safety factor (the Output Torque row lists the rating), then confirm the actuator-side flange matches your actuator's flange dimensions, and the valve-side flange (F05–F16) and stem bore match the valve stem. See our selection guide for a step-by-step method.

Which valves can the SD series be mounted on?

Butterfly, ball and plug valves with 90° quarter-turn travel. The valve-side mounting flange follows ISO 5211, and the stem bore and mounting height comply with international standards, so the gearbox assembles directly onto the valve.

What housing material does the SD series use?

Small-torque SD models use an ADC12 die-cast aluminum housing, which keeps the gearbox compact and light and makes it a cost-effective choice for volume orders; larger models use ductile iron for higher strength. Both versions share the same declutchable structure and quarter-turn worm drive.

SD Worm Valve Gearbox, 240–3,800 Nm

Name: SD Series Manual / Pneumatic Declutchable Quarter-turn Worm Valve Gearbox
Brand: YOYAGE

Manual / Pneumatic Declutchable YOYAGE SD manual / pneumatic declutchable worm valve gearbox for butterfly, ball and plug valves

Product Overview

SD Worm Gear Operator

The SD series is a compact quarter-turn worm gear operator with a pneumatic declutchable structure — mounted between a pneumatic actuator and the valve, it switches between pneumatic and manual handwheel operation, complementing the larger MY-F declutchable series with a smaller, more economical range. Seven sizes cover 240 to 3,800 Nm with ratios from 26:1 to 98:1. Small-torque models use an ADC12 die-cast aluminum housing that keeps size and weight down and suits volume procurement, while larger sizes use ductile iron; a four-row bearing combination and the self-locking worm gear pair keep transmission smooth, stable and efficient. Valve-side mounting follows ISO 5211; IP65 as standard, IP68 optional. Manufactured in compliance with CE and ISO 9001 standards.

Standard Type: Quarter-turn
Gear Type: Worm Gear
Ratio: 26:1–98:1
Torque: 240–3,800 Nm
Protection: IP65 (IP68 optional)
Housing Material: ADC12, Ductile Iron

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Product Features

Declutchable design switches between manual handwheel and pneumatic actuator operation
Self-locking worm gear set prevents valve back-driving
SS304 input shaft and small parts for corrosion resistance and long service life
C3/C5 coating system for surface protection
Reliable bearing support for stable operation
Grease-filled lubrication for extended service life
NBR seals for enhanced sealing performance
Rigorous torque and low-temperature testing

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Custom Solutions

Handwheel & chainwheel size customization
Pneumatic actuator connecting flange customization
Worm gear hubs customization (Valve stem)
MSS flange standard or custom connections
C5 coating system
IP68 protection option

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Technical Parameters & Dimensions

Read our selection guide: How to Choose a Valve Gearbox for Industrial Valve Applications

(Tip: Hold Shift and scroll the mouse wheel to scroll the table horizontallyPinch to zoom the table, double-tap to reset)

Dimension Drawing A · B · C · D1 · D2 · E · F · G1 · G2 · G3 · H1 · H2 · H3 · H4 · HW

YOYAGE SD pneumatic declutchable worm valve gearbox dimension drawing with ISO 5211 mounting flange and actuator connection details

Technical Parameters & Connection Size

Model	AT Double ActionDA	AT Spring ReturnSR	Ratio	Output TorqueN·m	A	B	C	D1Flange	D2Flange	E	F	G1Flange	G2Flange	G3Φ	H1Bore	H2Bore	H3	H4	HandwheelΦ
SD-1	DA52-105	SR52-92	26:1	240	115	89.5	105	F05	F07	143	196	F05	F07	Φ57	□14	□14	15	22	170
SD-2	DA105-125	SR105-125	28:1	600	135	120	113	F07	F10	178	245	F07	F10	Φ70	□17	□17	20	26	190
SD-3	DA140-160	SR125-140	38:1	900	160	133	131	F07	F10/F12	200	271	F07	F10/F12	Φ89	□22	□22	22	28	270
SD-4	DA190-210	SR160-190	54:1	1600	202	180	167	F10	F12/F14	280	370	F10	F12/F14	Φ108	□27	□27	29	32	300
SD-5	DA210-240	SR190-210	80:1	2100	245	221	186	F14	F16	348	458	F14	F16	Φ108	□36	□36	40	43	400
SD-6	DA240-270	SR210-240	78:1	3000	280	251	205	/	F16	378	498	F14	F16	Φ159	□46	□46	50	52	500
SD-7	DA270-300	SR240-270	98:1	3800	315	286	205	Φ200	F16	395	520	Φ200	F16	Φ159	□46	□46	50	52	550

Need SD Series Selection Support?

Send your valve type, torque requirement and pneumatic actuator details to the YOYAGE team for SD selection and quotation.

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SD Series Manual / Pneumatic Declutchable Quarter-turn Worm Valve Gearbox