Hydraulic Spring Return Actuator (Type HSTP - F)

BESI Marine Systems GmbH produces reliable and robust hydraulic single-acting spring return actuators.


The HSTP-F actuator may be installed in any place - submerged in medium, in dry spaces, on deck, or in hazardous areas.

Position Response

The valve position is determined by limit switches mounted externally on the actuator, or by volume transmitters installed inside the central control unit, such as the solenoid valve cabinet. The BESI volume transmitters are accepted by all major classification societies and are type-approved by Germanischer Lloyd (GL). They provide an inexpensive but very precise and reliable signal transmission and eliminate the need for any electric cabling to the valves. This ensures economic installation even in hazardous areas of a ship.

Emergency Operation

As a unique safety feature, the actuator provides a second independent piston for manual operation. It allows an emergency operation to be undertaken completely independent from the hydraulic circuit ? important in situations where the hydraulic circuit may be defective. For manual operation, a portable hand-pump can be connected to the actuator via a quick connector coupling.

The main advantages of the Type HSTP-F actuators include

  • Designed to ensure a defined fail-to-safe position - open or closed - even without control power.
  • Spring Discs instead of spiral springs are used to allow the actuator to operate even with 30% defective springs.
  • Economical installation - whether as single unit or ready-installed in a system - due to single-line connection. Single-acting ¼ -turn actuators need only one hydraulic supply pipe.
  • Operation of high oil pressure levels of 100 up to 135 bar, and up to 160 bar on request.
  • Small, compact overall dimensions.
  • Wide range of torques. Opening torques range from 190 Nm up to 7.730 Nm and closing torques from 100 Nm to 4050 Nm.


Type Torque (Nm) Weight (kg)
close open
HSTP 51 - 40/F 100 190 11,0
HSTP 78 - 40/F 170 280 20,0
HSTP 78 - 63/F 420 690 32,0
HSTP 108 - 63/F 750 840 55,0
HSTP 108 - 90/F 1100 2145 72,0
HSTP 156 - 100/F 2025 3865 92,0
HST2P 156 - 100/F 4050 7730 200,0
ISO 9001 certified

BESI Marine Systems GmbH
Vorweide 4
D-28259 Bremen