How to Select the Right Valve Gearbox

Part-turn Valve Gearbox (Quarter-turn Valve Gearbox)

A part-turn gearbox rotates the valve stem through approximately 90° to move the valve between fully open and fully closed. It is the standard structure for quarter-turn valves such as ball, butterfly, and plug valves.

YOYAGE part-turn valve gearboxes cover an output torque range of 240 to 850,000 Nm with manual, electric, or pneumatic operation options.

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Multi-turn Valve Gearbox

A multi-turn gearbox rotates the valve stem through multiple full turns to open or close the valve. It is used for rising-stem and non-rising-stem gate and globe valves, where the stem travel is long and the required turns far exceed a quarter turn.

Multi-turn gearboxes are typically built on bevel or spur gear stages and work together with stem nuts that convert rotation into linear stem movement. YOYAGE multi-turn valve gearboxes cover an output torque range of 216 to 170,000 Nm.

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Worm Valve Gearbox

A worm gearbox transmits motion through a worm screw meshing with a worm wheel. The meshing angle provides a large reduction ratio in a single stage — YOYAGE worm gear ratios cover 24:1 to 8860:1 — and gives the gearbox a self-locking characteristic, meaning the valve position is held without an external brake.

Worm gearboxes are the typical structure for quarter-turn (part-turn) valves — ball, butterfly, and plug valves — offering compact size and smooth, low-noise transmission.

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Bevel Valve Gearbox

A bevel gearbox transmits motion through a pair of bevel gears, changing the input direction by 90° while keeping high transmission efficiency. Bevel gear ratios at YOYAGE cover 2.35:1 to 924:1.

Bevel gearboxes are widely used on linear-travel, multi-turn gate and globe valves, especially where higher efficiency and larger output torque are required, or where the input shaft must be perpendicular to the valve stem.

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Spur Valve Gearbox

A spur gearbox uses parallel spur gears for reduction. In the YOYAGE range, the YZ-ZC series spur gearbox is combined with base models to build higher-torque, higher-ratio combinations — models carrying the S suffix (such as MY-1S and YZ-S) add a spur gear stage to the base gearbox.

It offers high efficiency and a simple, robust structure, serving linear-travel, multi-turn gate and globe valves — either combined with a base gearbox, or driving the valve directly, such as on buried-service valves where the input sits directly above the valve.

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Ductile Iron

Ductile iron is the standard housing material for YOYAGE valve gearboxes. Compared with grey cast iron, its nodular graphite structure provides much higher strength and toughness — typical grades such as QT450-10 deliver a tensile strength of ≥450 MPa and elongation of ≥10% — with good machinability and cost efficiency.

It suits general industrial environments such as water treatment, HVAC, and standard pipeline service at ambient temperatures from roughly -20°C to +120°C.

WCB Cast Steel

WCB is a cast carbon steel grade offering higher strength and better impact resistance than ductile iron — tensile strength ≥485 MPa and yield strength ≥250 MPa per ASTM A216. It is selected for gearboxes working under heavier loads, higher mechanical stress, or more demanding structural requirements, with a typical service range of -29°C to +425°C.

CF8/CF8M (SS304/316) Cast Stainless Steel

CF8 and CF8M are cast stainless steel grades equivalent to SS304 and SS316, with tensile strength ≥485 MPa per ASTM A351. CF8M adds 2–3% molybdenum for superior resistance to pitting and chloride attack. They are used for gearboxes installed in chemical plants, marine environments, and other corrosive atmospheres where standard painted housings are not sufficient.

LCC/LCB/LC1 Low-temperature Cast Steel

LCC, LCB and LC1 are cast steel grades designed for low-temperature service — LCC is impact-tested down to -59°C per ASTM A352, maintaining a tensile strength of ≥485 MPa. They are specified for gearboxes in cold-region installations, refrigeration, and cryogenic-adjacent applications where ordinary carbon steel would become brittle.

20CrMnTi Case-hardening Gear Steel

20CrMnTi is an alloy gear steel used for the internal gears of YOYAGE gearboxes. After carburizing and quenching, the tooth surface reaches HRC 58–62 for high hardness and wear resistance, while the core stays at HRC 30–45 and remains tough, giving the gears long fatigue life under repeated load cycles.

Solid Bronze Worm Wheel

A solid bronze worm wheel is machined entirely from bronze. Bronze runs against the steel worm with low friction and excellent anti-seizure behavior, making solid bronze wheels the premium choice for high-torque, long-service-life, or frequently operated gearboxes.

Bronze-rimmed Worm Wheel

A bronze-rimmed worm wheel combines a bronze toothed rim with a cast iron or steel center. The bronze rim provides the same low-friction, wear-resistant meshing surface where it matters, while the composite structure keeps the cost lower than a solid bronze wheel — a balanced option for standard applications.

Electric Actuator Drive

In an electric actuator drive, the handwheel input of the gearbox is replaced by a mounting flange that connects to an electric actuator, forming an actuator–gearbox combination. In YOYAGE model naming, electric-actuator-driven versions carry the D suffix — for example MY-D, MY-1S D, and YZ-D.

The actuator flange follows standards such as ISO 5210, so the combination can be matched to mainstream electric actuators.

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Manual Drive

A manual gearbox is operated by a handwheel mounted on the input shaft. The YOYAGE base manual series — MY, MY-V, YZ, and YZ-ZC — are built from their respective gear types and suit smaller torques and gear ratios; the S suffix (MY-1S, YZ-S) adds a spur gear stage for higher torque and ratio in manual operation.

Manual drive is the most common and economical configuration for valves that do not require remote or automatic control.

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Manual / Pneumatic Separated (Declutchable)

A declutchable gearbox sits between a pneumatic actuator and the valve, separating manual and pneumatic operation. In normal service the pneumatic actuator drives the valve through the gearbox; when air supply fails or manual operation is needed, the operator disengages the pneumatic side and drives the valve by handwheel.

This design keeps both control modes independent and safe, and is widely used on automated valves that must remain operable during power or air failure.

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Input Torque

Input torque is the torque applied at the gearbox input — by a handwheel, an electric actuator, or another driving device. Together with the gear ratio and transmission efficiency, it determines the output torque delivered to the valve stem.

For electric combinations, the actuator's output torque becomes the gearbox input torque, so the gear ratio must be matched accordingly during selection.

Output Torque

Output torque is the torque the gearbox delivers to the valve stem — the decisive parameter in model selection. The rated output torque of the selected gearbox must exceed the valve's required torque, including a safety factor, and should be the closest rating above that requirement.

YOYAGE part-turn valve gearboxes cover 240 to 850,000 Nm, and multi-turn valve gearboxes cover 216 to 170,000 Nm.

Mounting Flange

The mounting flange connects the gearbox to the valve top flange. YOYAGE standard connection dimensions comply with ISO 5211, ISO 5210, and JB 2920-81, covering the common valve-side and actuator-side interfaces.

During selection, the flange of the chosen model must be verified against the valve's top flange dimensions. Non-standard flange dimensions can be customized on request.

Worm Gear Hubs

The worm gear hub is the bored center of the worm wheel that couples the gearbox output to the valve stem. Within the maximum stem capacity of each model, YOYAGE machines worm gear hubs to match the customer's stem dimensions — including keyed, square bore, and other connection types.

Hub bore and keyway dimensions are verified during selection to ensure the stem connection matches the valve.

Stem Nuts

In multi-turn gearboxes, the stem nut converts the gearbox's rotation into the linear movement of a rising valve stem. Stem nuts are machined to the valve stem's thread or bore specification, including trapezoidal thread, keyed, and square bore connections.

Like worm gear hubs, stem nuts are matched to the customer's stem dimensions within each model's maximum stem capacity.

Gear Ratio

The gear ratio expresses how many input turns produce one output turn. Through this reduction structure, the input force is amplified to deliver greater output torque for driving the valve. A higher ratio means more output torque from the same input, but slower operation. YOYAGE standard ratios cover 24:1 to 8860:1 for worm gearboxes and 2.35:1 to 924:1 for bevel gearboxes, which already meet most application scenarios.

For ratios beyond the standard range, additional customization is available subject to minimum order quantities.

Handwheel

The handwheel is the manual input device of the gearbox. Its diameter determines the rim effort a single operator can apply: a larger handwheel delivers more input torque at the same hand force.

Standard handwheel sizes are provided with most models and sized to the rated torque. Custom handwheel dimensions — and chainwheel versions for overhead or remote operation — are available based on installation space and input torque requirements.

IP Protection Rating

The IP (Ingress Protection) rating defines how well the gearbox enclosure resists dust and water. Standard YOYAGE gearboxes are sealed for general industrial environments at IP67 level.

For special waterproof environments — such as outdoor, high-humidity, or buried service — IP68 upgrades are available with enhanced sealing designs.

Coating System

The coating system protects the gearbox housing from atmospheric corrosion. The standard coating suits general indoor and outdoor service.

For corrosive environments such as marine, chemical, and coastal installations, higher-grade coating systems — including the C3 and C5 corrosion categories per ISO 12944 — are available on request.