Unholtz Dickie Corp
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Long Stroke Thrusters

The LS Series Long Stroke Thruster Test Systems are highly regarded as the industry standard for long stroke transient testing. This equipment is used in the design and production test of automotive airbag sensors by leading suppliers of automotive airbags and associative control modules.

Used for development and test of front and side airbag sensors, the LS Series thrusters are designed to produce highly accurate and repeatable acceleration pulses in the horizontal plane. Pulse types include classical, haversine, halfsine waveforms, as well as reproduction of actual crash waveforms imported as ACSII amplitude/time history or as a transient capture. The long stroke capability and the powerful SA Series power amplifier can reproduce crash waveforms with velocity changes up to 45 MPH (72 KPH).

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  • Max force 2,500 –8,500 lbf (11 to 38 kN) depending on configuration
  • 350 to 800 in/s (20-45 MPH, 32-72 KPH) velocity change
  • 8, 12, 16, 20, 24 inch (203-610 mm) stroke configurations
  • Up to 400 g, 8 msec - halfsine with 2 lb payload
  • Isolated bearing guided slider
  • Modular, high-efficiency SA Series Class D power amplifiers
  • Ultra-rugged, reliable Silicon Carbide (SiC) MOSFET Technology
  • All air-cooled system
  • Automatic slider positioning (center or end)
  • APEX Series Control Systems

Wide Performance Envelope

Enhancements in amplifier technology, specifically the Unholtz-Dickie SA Series, have increased system performance as compared to thrusters using linear type power amplifiers. Coupled with the high performance SA Series amplifier, the LS Series thrusters now provide increased shock force for testing larger packages and increased velocity changes representative of longer duration pulses.


Both the LS Series thruster and the SA Series power amplifier are air-cooled, an important feature that boosts reliability and reduces the cost of installation and operation and minimizes floor space requirements.

Rugged, Lightweight Armature and Slider

The LS was designed for reliable and repetitive high acceleration pulse applications and features a high strength aluminum alloy armature and a rugged bearing guided slider assembly for mounting the test specimen and fixture. The standard slider size is 6 x 7 inches (152 x 178 mm). An optional low mass fixture is available for testing payloads up to a 2 lb to extremely high velocity changes. A relay activated closure or manual switch input can be used to set the starting position of the slider at either the center or end of travel allowing for maximum velocity change (center) or maximum unidirectional displacement (end).

Isolated Supporting Base

The LS Thruster is mounted on a rigid steel base structure that includes the Integrated Guidance Isolation System. IGIS provides vibration isolation of the shaker body and limits pitching of the shaker during tests to ensure linear motion.

Safety Shield

A balanced and hinged plexi-glass safety shield is included as standard with the thruster. This shield is also integrated into the control interlock circuit. Should the shield be lifted during operation, the shaker control system will abort the test.

Industry Applications

Operating in companies throughout the world, Unholtz-Dickie’s thrusters dominate the field of airbag shock test systems providing unmatched performance and waveform accuracy. Applications vary, with some systems operated manually, while other systems have been successfully integrated into automated production lines running 3 shifts a day, seven days a week.

When combined with an APEX Series Vibration Control System, many different types of shock pulses can be produced with great accuracy and fast repetition rate. A special remote interface is also available for automated control. Through this interface, specific test types can be selected and run. The APEX Series Control Systems can be used to reproduce the following shock waveforms:

  • Halfsine
  • Sawtooth
  • Trapezoid
  • Haversine
  • Capture crash pulse
  • User defined (Import ASCII)

A complement of signal conditioners and accelerometers specifically designed for shock applications is available to provide optimal performance for low-frequency shock applications.


Typical Haversine test waveform used for airbag sensor testing (10 ms, 20 miles per hour). The graph provides graphical information on the associated velocity and acceleration waveforms. Pre and post compensation pulses are included for displacement and velocity optimization. Coast times are selectable.

Crash Pulse

An actual captured crash waveform is used as a reference test pulse. The top graph depicts the velocity waveform, and the bottom graph the acceleration waveform. Other pertinent graphical information can be displayed as needed including response measurements, % deviation, and drive output. The above waveform shows a zero pre pulse and a braking post pulse. For this test the thruster is initially positioned at one end for unidirectional operation.