Despite their compact design, Thomson Warner Linear's H-Track actuators can move loads of up to 21,350 Newtons. This makes them suitable for applications with limited space that require high adjustment force and shock resistance. These include, for example, the actuation of a snow plough blade, plows and spray bars in agriculture, mower lifts or the tipping troughs of smaller commercial vehicles.

"It is now possible to specify components that deliver high force in a compact format, while still enjoying the benefits of an electrically driven actuator," explains Anders Karlsson, product specialist for linear actuators at Thomson. The concept of an expansion tank and pump configuration results in a miniature hydraulic system. "The result is an extremely compact electro-hydraulic actuator that is designed for high loads and can withstand even high shock loads because the fluid-supported actuator protects the actuator components through damping," says Karlsson.

Force density and impact resistance
Systems with hydraulic cylinders require a complex structure of hoses, pumps, valves and expansion tanks. This infrastructure is usually quite costly to install, use and maintain, while the fluid itself requires careful handling. The H-Track actuators solve this problem by means of a miniaturized hydraulic pump driven by a DC motor. The pump, cylinder and expansion tank form a self-sufficient unit that fits into a compact housing about the size of a ball screw actuator. This hybrid actuator has a nominal force of 21 kilonewtons and achieves travel speeds of just under 100 millimetres per second. Users can choose between different pump and motor versions to optimize their system for a higher load rating or speed than would normally be possible with ball screws.

The use of hydraulic power to generate a linear movement also provides effective damping as a side effect. As a result, such a system can withstand shock loads that would otherwise bend the ball screw or piston rod - especially if the shock load occurs when the actuator is extended.

Flexible configuration and application options
The ability to configure multiple pump and cylinder sizes allows Thomson to produce variants of the H-Track with individual speeds and load ratings. The unique pump and reservoir architecture also minimizes the number of components while optimizing the volume/pressure differential. A patented double tank shuttle valve with back pressure equalization further increases efficiency.