Hydraulic starting systems

Hydraulic systems & components

1st Quarter 2010 Hydraulic systems & components

Hydraulic starting dates back to at least World War II, when the military needed an alternate and more reliable means than electric starting for their landing craft.

Basic principles

All starter systems, whether electric or hydraulic, operate on common principles. Energy has to be stored and then released on command to crank and start a combustion engine.

Whereas in an electrically operated system the energy store is a battery, in a hydraulic starter the energy source is provided by:

* A recharge pump driven by the engine.

* An electrically driven pump.

* A manually operated pump.

This energy is stored in the accumulator as hydraulic oil under pressure. When the oil is released by a foot-operated valve it turns the starter motor.

Advantages

Hydraulic starters have many advantages over conventional electric systems:

* The system is totally enclosed and lubricated. Any adverse environmental conditions are not detrimental to the starting system.

* The energy can be stored indefinitely providing the system is installed and maintained to specifications. Batteries only hold their charge for a limited period.

* For all practical purposes, the system is temperature independent as long as the correct oil viscosity is used. Batteries dislike being subjected to highs and lows in temperature and lose their charge rapidly when temperatures drop well below 0°C.

* It is possible to manually recharge a hydraulic system in a matter of minutes.

* Being non-electric, the systems are safe for use in explosive environments.

* The starter motors have a very flat torque curve in comparison to electric starters.

Case studies

Snowbird 6

The crossing from New York to London overland via the Bering Strait was attempted unsuccessfully five times. Conditions of minus 50°C are experienced on this route and at times the expedition vehicle had to endure submersion in freezing water and ice. The failed attempts were plagued by electric starting problems. For the sixth attempt Powerstart co-sponsored the hydraulic starting system and a successful crossing was achieved.

Foster Wheeler (Durban)

The client required a pneumatically operated and recharged starting system at a chemical plant. Due to the hazardous nature of the environment, a system was designed which had no electrical components whatsoever. The recharging of the system was effected by a small pneumatically operated hydraulic intensifier. The starting was performed via pneumatically operated valves and the system featured a hand pump for manual recharge.

Powerstart products are manufactured and distributed by Powerworks, a Midrand-based company responsible for design, development, manufacturing, repairs and sales of the product range since the early 1980s.

For more information contact Nick Ruberg, Powerworks, +27 (0)11 203 9900, [email protected], www.pwrstart.com

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Hydraulic starting systems

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