Busak+Shamban provide a sealing solution incorporating specialTurcon®Stepseal® K and Excluder® to FOX-VPS, hydraulic cylindermanufacturers, who supply Roger Bullivant Ltd., a majormanufacturer of piling equipment with cylinders for their hammers.On their new generation of patented quiet hammer, which aredesigned to run at higher pressures and speeds, the seals withinthe cylinders were failing. The problem was solved by convertingcomposite seals to Busak+Shamban Turcon® Stepseal® with a specialprofile to prevent tilting in rapid reversal situations. Inaddition, to avoid media ingress, wipers were changed toBusak+Shamban Excluder®.
To meet the UK government’s target for build of ‘affordable’housing, there is a trend for new buildings to be of modularconstruction, with a piled foundation; a method that is quicker andeasier than digging traditional footings and negating the risk ofsubsidence.
To further reduce costs and accelerate build, standard hammersfor sinking the piles are being replaced by high-speed hammers. In1990, a typical piling hammer would only operate at 40 to 50 blowsper minutes, whilst the latest hammers work at around 120 blows perminute. Consequentially there is an increased noise level, causingsignificant noise pollution, which has become subject to health andsafety restrictions when piling machines are used on sites close tooccupied buildings. Roger Bullivant Ltd., a major piling company inthe UK, who manufacture their own equipment, have, in response,developed a patented ‘quiet’ hammer, to operate at a lower level ofnoise.
One of the latest series of Roger Bullivant pile drivinghammers, utilising advanced FOX-VPS hydraulics and Busak+Shambansealing solutions.
The Camberley, Surrey, based company FOX-VPS, faced thechallenge of designing and manufacturing a hydraulic cylinder forthis new series of hammer, capable of withstanding elevatedpressures and intensified flow of hydraulic oil.
Traditionally, composite seals are fitted in the hydrauliccylinders for these hammers. However, on this new generation ofmachine, the existing seal arrangement exhibited leakage andpremature failure. Busak+Shamban, worked with FOX-VPS to identify anew configuration which could guarantee sealing integrity andextend service life.
To reduce friction the proprietary PTFE material, Turcon® waschosen and Turcon® Stepseal® K, fitting into existing seal grooves,was investigated as an option. Though these performed well, due tothe velocity and length of stroke of the hammers, the hydrauliccylinder was occasionally subject to extremely rapid reversal,which caused the seal to tip over.
To prevent this from occurring, FOX-VPS redesigned theirhousing. They added a reservoir between seals to reduce inter-sealpressure and tightened housing tolerances.
Busak+Shamban also recommended a design change to the standardTurcon®Stepseal® K and, in addition, FOX-VPS improved finishes andsurfaces to ease assembly, reduce risk of seal damage and increaseseal life. Wipers used in the sealing arrangement were replacedwith Excluder®, to avoid ingress of aggressive media from thehostile environment associated with hammer operation.
FOX-VPS, in collaboration with Busak+Shamban, turned around asituation where seals were leaking and cylinder service life wasshortened into one where they are able to offer a stable productexhibiting exceptional sealing integrity.
Stuart Franklin, Technical Director of FOX-VPS, is pleased withthe level of support provided by Busak+Shamban. He comments: "Acylinder is only as good as the seals you put in it. The cost ofseals may be half a percent of the total cylinder cost but it iscritical that they work effectively. If they do not, neither willthe cylinder."
Background to FOX-VPS:
Camberley based FOX-VPS was formed in January 2004 through theamalgamation of two established companies, Fox Engineering andVisual Planning Systems. They design and manufacture hydrauliccylinders, fire fighting equipment for airport crash tenders andundertake subcontract machining, welding and assembly.