AUMA SA and GST Multi-Turn Actuator with Spur Gearbox

Overview

AUMA SA and GST is the combination of an AUMA SA multi-turn actuator with a GST spur gearbox, used when the drive shaft of the actuator has to sit at a defined offset to the valve stem rather than directly in line with it. A spur gearbox keeps input and output shafts parallel but displaced, which lets the actuator be placed beside the valve, clear of walkways, handwheels and stem protection tubes, while still multiplying output torque considerably. The AUMA SA and GST covers valve torques from 120 Nm up to 16,000 Nm and is configured around the SA 07.2 to SA 16.2 and SA 25.1 to SA 48.1 actuator families.

This page describes the complete actuator-plus-gearbox package; the standalone gearbox is covered on our separate AUMA GST product page. Seven Star LLC supplies the AUMA SA and GST on request to water, power, desalination and oil and gas customers across the Sultanate of Oman and the GCC, pairing actuator, gearbox, flange and controls into one documented delivery.

Working Principle of the AUMA SA and GST

The SA actuator drives the input shaft of the GST gearbox, and a train of spur gears reduces the speed and raises the torque before the output drive sleeve turns the valve stem. Reduction ratios run from 1:1 on the GST 10.1 to 22:1 on the GST 40.1, with intermediate steps such as 1.4:1, 2.8:1, 5.6:1 and 8:1. The torque at the valve equals the actuator torque multiplied by the ratio and gearbox efficiency; AUMA publishes the conversion factor for every ratio, from 0.9 up to 19.8, so that actuator input torque can be calculated directly from the valve torque, with an extra 15 % input torque recommended for new gearboxes.

Because the gearbox is mechanically simple and has no relative motion between input and output axes other than rotation, it adds torque capacity without adding control complexity. The actuator’s own torque and limit switching continue to protect the valve, and a handwheel on the gearbox provides motor-independent manual operation. The gearbox must be matched to the actuator’s mounting flange and weight: for example, a GST 14.1 accepts SA 10.2 on an F10 input flange or SA 14.2 on an F14 flange, within permissible actuator weights of 40 kg and 80 kg respectively.

Engineering Design of the AUMA SA and GST

The GST range is built in the sizes GST 10.1, 14.1, 14.5, 16.1, 25.1, 30.1, 35.1 and 40.1, with output flanges to EN ISO 5210 from F10 to F40 and DIN 3210 from G0 to G7. Gearbox weights run from about 14 kg for the GST 10.1 to approximately 255 kg for the GST 40.1. For standard reduction ratios the input shaft is stainless steel, and input shafts with a second shaft end or a protective cap are available for handwheel or tool operation. The maximum permissible input speed is 240 rpm.

Enclosure protection is IP67 or IP68, depending on the actuator in the combination, and corrosion protection is class KS with a double-layer powder coating. The gearbox operates over –40 °C to +80 °C on its own, while the combination as listed by AUMA is rated for the actuator’s range. Mounting position is unrestricted, the handwheel is aluminium with a ball handle as standard, and power-tool emergency operation and the GW reversing gearbox are options. The gearbox meets the lifetime requirements of EN ISO 22109.

Key Features

The following characteristics define the AUMA SA and GST combination:

• A spur gearbox positions the actuator at an offset to the valve stem, freeing the stem axis for handwheels, extensions and protection tubes.
• Valve torques from 120 Nm to 16,000 Nm are reached through ratios from 1:1 to 22:1 across eight gearbox sizes.
• Full compatibility with SA 07.2 to SA 16.2 and SA 25.1 to SA 48.1 actuators means one family of controls, spares and commissioning tools.
• Published conversion factors for each ratio simplify the sizing of actuator input torque.
• A stainless steel input shaft, optional second shaft end and protective cap suit wet and exposed installations.
• Valve attachments to EN ISO 5210 F10 to F40 and DIN 3210 G0 to G7 cover the common gate and globe valve interfaces.
• A handwheel with ball handle, with cast-iron and lockable options, provides motor-independent manual operation.
• Ambient temperature of –40 °C to +80 °C for the gearbox and KS corrosion protection suit harsh outdoor sites.

Industrial Applications

The AUMA SA and GST is used on large isolation gate valves in water transmission mains and desalination intakes, on penstock and sluice gates where the actuator must stand clear of the stem, and on globe and gate valves in power-station cooling-water and fire-water systems. Offset mounting is also valuable in congested valve pits, pump-house galleries and skid-mounted process units, where space around the valve stem is limited and the actuator has to be set on a bracket at one side.

In the Sultanate of Oman the combination suits the transmission pump stations and reservoir inlets of the national water network, the seawater and brine valves around Sohar, Barka and Salalah desalination plants, and the industrial water systems of Duqm and the interior oil and gas fields. Seven Star LLC supplies the AUMA SA and GST with selection support, including actuator weight checks, flange matching and the choice between spur (GST), bevel (GK) and worm (GHT) gearboxes for each installation.

Technical Specifications

The table summarises the main data of the AUMA SA and GST combination from the AUMA product page and the technical data sheet for GST 10.1 to GST 40.1.

Request a Quote for AUMA SA and GST

To request a quotation for the AUMA SA and GST, send Seven Star LLC the valve type, open and close torque, stem diameter, mounting flange and the space available for the actuator. Our instrumentation division will size the combination and provide an RFQ response, and the technical datasheet can be downloaded from this page. In Oman and the GCC, we supply the product with manufacturer documentation and local support, and can advise on lead times and availability.