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Product category: Springs, dampers, latches, locks and small components
News Release from: Lee Spring | Subject: PowerSpring
Edited by the Engineeringtalk Editorial Team on 20 June 2003

Hydraulic breaker assisted by novel
springs

A revolutionary design of excavator-mounted hydraulic breaker incorporates equally ground-breaking PowerSpring technology.

A revolutionary design of excavator-mounted hydraulic breaker that is significantly more powerful, vastly quieter and up to three times more efficient than conventional breakers, incorporates equally ground-breaking PowerSpring technology developed by Ibex and available in the UK through Lee Spring This application represents the first major application for PowerSpring following extensive testing and trials by Hammertech, designer of the hydraulic breaker, which launched the product at the SED plant show in April where it attracted serious interest from construction and demolition experts

Power generation based on energy rather than frequency is what makes this breaker so different from others.

The breaker uses an innovative combination of proven hydraulic and power spring technologies which enable it to operate at much lower striking rates and generate considerably higher impact energy/blow (500 to 1000J per blow on units produced so far) than standard hydraulic breakers of equivalent size.

The slower, more powerful striking rate of about 70 blows per minute of HammerTech breakers results in a far more efficient transfer of impact energy through the chisel and into the material being broken.

Conventional higher frequency breakers work at striking rates of up to 2000 blows per minute and tend to 'drill' the chisel through material.

The slower striking rate of the new breaker reduces wear on the chisel and its bushes while dramatically reducing noise levels.

Another significant benefit is the virtual elimination of vibration which results in much less fatigue for the host machine and its operator.

Whereas conventional breaker systems can require greasing every half hour, this new design creates a unit that is practically maintenance-free and hence more productive.

The breaker operating mechanism is extremely simple.

It incorporates a hydraulic cylinder that lifts the main impacting drop weight inside a guide sleeve.

The drop weight is also attached to PowerSprings which are tensioned as the ram is lifted.

At the top of the stroke a reciprocating flow control valve automatically releases and reverses the flow in the cylinder, allowing the tensioned springs to pull the drop weight down at high speed (4m/s) to hit the chisel.

PowerSprings are flexible, high strength tension/extension springs manufactured from a natural rubber core enclosed in braided fibre inner and outer covers.

Tested to over 5 million cycles the springs have double the energy storage of normal steel springs.

A standard 32mm diameter PowerSpring delivers 3.5kN at 90% elongation.

With virtually no restriction on length and terminations to suit most applications, PowerSpring opens up new design possibilities and applications where energy and propulsion, dampening, shock absorption or retainer mechanisms are required.

Essential to this success of this application was the custom spring termination developed by Ibex which had to be compact and exceptionally strong.

Due to the high impact loads experienced a special machined conical termination was designed to combine with the rubber filaments that are epoxy bonded into a metal fitting.

The springs had to meet a minimum of 3 million operating cycles which equates to 12 months working life of a typical hire fleet hammer.

Prior to acceptance, tests - carried out by the Institute of Spring Technology- proved that the springs were capable of in excess of 5 million load cycles, even at the high levels of load and elongation expected.

Currently, HammerTech has developed two types of hydraulic breaker to suit various different carrier weights.

The 500-2 weighs 200kg and is designed for use on carriers between 1 and 3.5t.

It develops impact energy of 500J per blow at the tool tip - verified by independent tests conducted by Sheffield Hallam University.

This is up to treble the impact energy of a similar weight standard hydraulic breaker fitted to this size excavator.

The 1000-4 develops impact energy of 1000J per blow at the tool tip and is designed for use on carriers between 2.5 and 7t.

This breaker weighs approximately 280kg and its impact energy is equivalent to that of a standard breaker for a 7-12t class excavator.

Breakers can be top or side mounted and have an integral fixed hydraulic oil pressure and flow valve to automatically regulate supply from the host excavator's normal auxiliary circuit.

Both designs are protected by worldwide patents. Request a free brochure from Lee Spring ...

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