Automating multi-turn valves (gate and globe valves with rising stems) means converting the actuator's rotation through redirection and reduction to drive the stem continuously — the job of the GK multi-turn bevel gearbox (600–15,000 N·m), the BST multi-turn spur gearbox (1,500–20,000 N·m) and the GZ series (300–15,000 N·m, ratios 2–36). All three are ex stock at about 1/2–1/3 the price of comparable imported units, fitting all major electric actuator brands (ISO 5210), custom sizes on request. Selection tables and multi-turn sizing guidance below.
The GK bevel stage redirects the actuator's horizontal rotation into the stem axis, with an integral bronze stem-nut — the stem passes through the nut and rotation converts directly to travel. A protective guard shields the exposed stem. Selection table:
| Model | Ratio (base/R) | Max. stem ød5 | Input flange | Output flange (std/opt) | Max. output torque N·m |
|---|---|---|---|---|---|
| GK14.6 | 3/4/6 (8/12) | 45 | F10·F14 | F14 / F10 | 600 |
| GK16.2 | 3/4/5/6 (8/10/12) | 65 | F14·F10 | F16 / F14 | 1,500 |
| GK25.2 | 3/4/5/6 (8/10/12/16) | 75 | F14·F16 | F25 / F16 | 2,500 |
| GK30.2 | 3/4/5/6 (8/10/12/16/20) | 80 | F14·F16·F25 | F30 / F25·F35 | 5,000 |
| GK35.2 | 6/8 (12/18/24/36) | 100 | F25·F16 | F30 / F25·F35 | 8,800 |
| GK40.2 | 5 (10/15/20/25/30) | 130 | F25·F16 | F40 / F35 | 15,000 |
Construction details: GK14.6–GK25.2 stem nuts run trapezoidal threads (reliable thrust self-locking); GK40.2's output is an M160×3 thread interface; input shafts ø20–50 mate F10–F30 flanges; the dimension tables carry bronze-nut height, guard height (140mm on GK14.6; 410–520mm from GK25.2 up) and every mounting parameter.
BST uses spur gearing — small ratios (2–8), high efficiency — for multi-turn valves where stroking time matters (small ratio = longer travel per turn):
| Model | Ratio | Max. bore | Input flange | Output flange | Max. output torque N·m |
|---|---|---|---|---|---|
| BST1.5 | 2/3/4/6/8 | 65 | F10·F14·F16 | F16 | 1,500 |
| BST8 | — | 100 | F14·F16·F25 | F30 | 8,000 |
| BST15 | — | 110 | F14·F16·F25·F30 | F35 | 15,000 |
| BST20 | — | 110 | F14·F16·F25·F30 | F40 | 20,000 |
BST dimension tables include overall dimensions (A/H2–H4/ød), input-shaft parameters for each flange option and the output-side max stem bore ødmax (65mm on BST1.5, 110mm on BST20).
GZ fills the ratio 2–36 band with output flanges F10–F30:
| Model | Ratio | Input flange | Output flange | Max. output torque N·m |
|---|---|---|---|---|
| GZ160.3 | 2–36 | F10 | F10 | 300 |
| GZ200.3 | 2–36 | F10·F14 | F14 | 750 |
| GZ250.3 | 2–36 | F10·F14·F16 | F16 | 1,500 |
| GZ40 | 2–30.25 | F14·F16·F25 | F25 | 5,000 |
| GZ45 | 2–36 | F16·F25 | F30 | 15,000 |
Typical duty: power-station and waterworks gate-valve banks (GK14.6–GK30.2), oil/gas pipeline globe valves (BST8–BST20), slow-motion discharge and vent valves (GK high-ratio R). The economics mirror the quarter-turn line: an imported multi-turn actuator plus imported gear pair usually costs far more than "a regular actuator + our GK/BST" — same output for about 1/2–1/3 the total price, with ex-stock delivery versus the typical 8–16 week import lead time. On retrofit and emergency-replacement projects, that lead-time gap is the deciding variable.
Buying tip: GK/BST/GZ fit all major electric actuator brands (ISO 5210 flanges), in stock, about 1/2–1/3 the price of comparable imported products, custom sizes on request.
Complete GK/BST/GZ tables and drawings (CN/EN PDFs): Gearbox Product Data download. Multi-turn sizing and quotes — submit an RFQ with valve type / stem diameter / stroking-time requirement.
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