AUMA GK 25.2 Bevel Gearbox (2,000 Nm)

Overview

AUMA GK 25.2 is the last single-stage size of the GK bevel gearbox family and the first to be rated at 2,000 Nm of valve torque with 800 Nm for modulating duty. It is used where a gate valve or globe valve is too large for an actuator to deliver the seating torque directly, or where the actuator has to be offset sideways, and it does so with only two ratios: 5.6:1 and 8:1. At 60 kg it is four times heavier than the GK 14.2 and more than seven times heavier than the GK 10.2, which reflects the much larger bevel gear set and housing.

In Oman and the GCC, Seven Star LLC supplies the AUMA GK 25.2 to water, power and process customers in the Sultanate of Oman and the GCC. We select between the two ratios on the basis of valve torque, available actuator and closing time, and we provide the gearbox with AUMA documentation and spare parts support.

Gear Train of the AUMA GK 25.2

The AUMA GK 25.2 uses a single stage of face-hobbed Palloid bevel gears, which AUMA chose for smooth meshing, low noise and high efficiency. The output drive sleeve is designed for the thrust of rising stems and can be fitted with a stem nut so that the gearbox operates as a screw jack, with a stem protection tube available for the rising stem. Optional position and end-position signalling during manual operation is available through a WSH limit switching device.

The 5.6:1 ratio has a conversion factor of 5.0 and needs 397 Nm of nominal input torque and 160 Nm of modulating input torque to deliver the full 2,000 Nm valve torque, while the 8:1 ratio has a factor of 7.2 and needs only 278 Nm nominal and 111 Nm modulating. Both ratios have a 30 mm input shaft. The average output torque for ATEX open-close duty is 600 Nm at 5.6:1 and 1,000 Nm at 8:1, and the standard handwheel is 630 mm for 5.6:1 and 500 mm for 8:1, with an 800 mm special handwheel.

Engineering Design of the AUMA GK 25.2

Valve attachment is F25 according to EN ISO 5210 (G4 according to DIN 3210), with output drive types A, B1, B2, B3 and B4 and several special attachments. The input flange is F14, so an SA 14.6 or SAR 14.6 can be mounted on the 5.6:1 ratio and an SA 14.2, SAR 14.2 or SA 14.6 on the 8:1 ratio, with a permissible actuator weight of 80 kg.

The housing carries a double-layer iron-mica powder coating for KS corrosion protection in AUMA silver-grey, achieves IP68 (8 m head of water for up to 96 hours) and mounts in any position. The temperature range is -40 to +80 degrees Celsius as standard, with -60 to +60 and 0 to +120 degree options, and the gearbox can be fitted with a GW 14.1 reversing gearbox to reverse the direction of rotation. Short-time duty S2-15 minutes applies to open-close service and intermittent duty S4-25 percent to modulating service.

Ratio Data of the AUMA GK 25.2

The two ratios of the AUMA GK 25.2 give the following input data in AUMA’s technical data sheet.

Both ratios carry the same 2,000 Nm valve torque, the same F25 flange and the same 60 kg weight.

Key Features

The AUMA GK 25.2 bridges the gap between small bevel gearboxes and the double-stage heavyweights:

• Right-angle bevel gearing delivers 2,000 Nm to the valve, or 800 Nm when the valve is modulated.
• The 5.6:1 and 8:1 ratios, with factors of 5.0 and 7.2, trade 397 Nm of input torque against 278 Nm.
• Face-hobbed Palloid gearing is used for quiet, efficient running and long life.
• An F25 flange with G4 option follows EN ISO 5210 and DIN 3210, with output drive types A and B1 to B4.
• SA 14.6 and SA 14.2 class actuators, with their SAR versions, fit on an F14 input flange up to 80 kg.
• The 60 kg housing includes the output drive sleeve and grease filling.
• Standard handwheels of 630 mm and 500 mm, with an 800 mm special, give a realistic manual fallback.
• Stem nut and stem protection tube options support rising-stem screw-jack service.

Industrial Applications

Large gate valves on seawater circulation lines, big globe valves on steam header isolation and large stop valves on pumping-station discharges commonly require the 2,000 Nm range provided by the AUMA GK 25.2. In Oman’s desalination and power plants the offset geometry lets the actuator sit beside the valve, and the 8:1 ratio keeps the input torque low enough that a mid-size actuator can still do the work. Manual-only installations also use the 630 mm handwheel on the 5.6:1 ratio for infrequently operated big valves.

In Oman and the GCC, Seven Star LLC supplies the AUMA GK 25.2 to EPC contractors and plant operators across Oman and the GCC, including utilities in the Sohar and Salalah economic zones. See also the AUMA GST spur gearbox family, review the AUMA SA 10.2 multi-turn actuator for lighter duty, and check the AUMA GS part-turn gearbox range if a quarter-turn output is required.

Related pages on our site: AUMA GK 16.2 and AUMA GK bevel gearbox family.

Technical Specifications

These AUMA GK 25.2 values come from the common GK 10.2 to GK 40.2 sheet.

Both ratios give the same valve torque, so the decision is the input torque of 397 Nm at 5.6:1 against 278 Nm at 8:1 and the matching actuator, SA 14.6 or SA 14.2.

Request a Quote for AUMA GK 25.2

Submit your RFQ for the AUMA GK 25.2 with the valve torque, the stem attachment and the actuator you intend to mount, and Seven Star LLC will confirm the ratio and quote delivery. The AUMA technical data sheet can be downloaded from this page, and our instrumentation team can help with stem protection tubes, handwheels and reversing gearboxes. In Oman and the GCC, we supply every gearbox on request, with lead time confirmed at quotation.