By wire controls compact costs

Hydraulic power achieves much higher power densities than electric, but adds cost and potential sources of trouble wherever there are exposed high pressure hoses.

Problem: Exposure, is, however, inevitable, if they have to be brought outside protected housings to connect to operator controlled valves. If torn, they can form serious sources of pollution and have to replaced with correct parts, because they cannot be patched. They also represent a significant cost item, especially if they have to be armoured. Solution: Mobile plant is increasingly turning to electrically operated valves. While these are increasingly accepted in the more sophisticated items of mobile plant, electrically actuated valves are now sufficiently price competitive to be the solution of choice in a Swedish made walk behind compactor. The latest Swepac compactors use Danaher Motion's E050 actuators to move the spool of a control valve, which changes the eccentricity and direction of rotation of the internal eccentric weight as it rotates. This has the effect of controlling the magnitude of the compaction vibrations and the direction of movement of the compactor. Applications: Any piece of mobile plant controlled by a human operator. Thomson actuators made by Danaher Motion cost from 100 to 250 euros (£70 to £170) and control boards from 200 to 500 euros (£135 to £345) depending on the complexity of the system. By not having to route hoses to operator positions, short hoses can be used instead of long ones. Long electric cables are much cheaper to install than hoses of the same length. They are lighter, more flexible, do not act as sources of heat or absorb energy through oil being pumped through them, do not lead to oil spillages if damaged and do not leak at oil at connectors. TS Danaher Motion Swepac