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Page 56
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It's the air apparent
Hyva's portfolio of hydraulic-powered tipper, hookloader and skip bodywork is well known in the UK, especially its Auto-Sheet for heavy-duty containers. Operated from a cab switch via the vehicle's PTOdriven hydraulics, its a regular choice with large fleets such as Sita and Onyx. Auto-Sheet retails at around E5,750; Hyva has sold nearly 300 systems since its 2001 introduction.
But Hyva's truck-powered sheets are different: instead of electric or electro-hydraulics, its autocovers move pneumatically, via the vehicle's air Supply. 'The electric motors and coil springs on some tipper sheets are prone to failure," says MD Tony Davies, "so we're using a twin-cylinder airactuator with diverter valve and the system is tapped into the tipper body's raise/lower valve".
A simple button in the cab operates the usual flip-over sheeting frame, unrolling the cover to the rear or letting it roll forward after loading up. The Hyva air system weighs in at just 60kg and is priced at around £2,500. To date 30 have gone into service, mostly with Swindonbased Earth line on muckaway duties.
Operators carrying loads such as quarry products, animal feed. grain or fertilizer have a wider choice. Dawbam & Sons' Clearspan rollovers feature the latest Hydro-Clear electro-hydraulic power pack; the firm reckons they are particularly durable. 'These trucks work in a tough environment but we're sure that our self-powered systems will prove more reliable long-term than all-electric ones," says director Ben Harrington. Operated from in-cab switches or remote controls, sturdy motors drive the lengthy draw-straps and the sheets' roll-over movement: sheet-lifting links for heaped loads are optional but manual overrides are standard. With aluminium end domes, sheet poles, hydraulic fittings and oil, the system adds 220kg to the chassis and 60kg to the trailer. Dawbarn's Hydro-Glide front-to-rear cover also has a power pack and bulkhead motors which slide the sheet forward along 8mm steel cables into the front dome before loading. The tarp is then simply retracted. A truck system weighs 140kg, or 170kg for a trailer.
Al hydraulic parts carry a 12-month fair-wear-andtear warranty the new designs can be retrofitted to existing Clearspan Dawbam's Hydro-Clear power pack is inside sheets. One operator the front dome on this Stas bulker doing just that is animal feed manufacturer ABN of Wolsingham. Its newest Bridge Bodies blowing trailers with Muldoon hydraulic rear steers are now being fitted with the DavVoarn remote hydraulic actuation kit. Fleet engineer Lindsey Sharp explains: 'It's extra weight and cost but they'll be quicker, safer and we won't spill product."