Whispering hammers

MANUFACTURERS of hydraulic hammers are being forced to make them quieter, largely following environmental legislation which originated in Germany a decade ago and is rapidly spreading.'Most of them have come up with a solution which involves wrapping the harnmer in a mattress-like material.

Krupp's Compact System, introduced three years ago, reduces the noise by 5 to 8 decibels. This means that when reduced by 8 decibels, the noise appears to be only.half as loud to the human ear. However, the modifications have reportedly added 12 per cent to 15 per cent to the hammers' cost.

Others have introduced hydraulic concrete crushers - scissor like crushers fitted to excavators which rip into concrete - as a substitute for the hammers. Environmentally, these have a further advantage over hammers, Their ability to separate the reinforcing bar from the concrete as they tear a building apart produces steel for recycling and pure concrete for fussy landfill sites.