Buy one and stop me
Page 19
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Road safety should be at the top of every self-respecting haulier's agenda so auxiliary braking systems make sense. We've sampled a 4-Series eight-legger fitted with the Swedish truck maker's hydraulic retarder and wonder why more Scania tipper operators don't invest in them.
by Bryan Jarvis • The development of Scania's 4-Series eliminated the old problem of shoe-horning a hydraulic retarder down behind the eightwheeler's gearbox: the new design features a slightly wider axle span which leaves much more space around the back of the box.
But when you've shelled out more than £60,000 on a chassis, plus the cost of a body, tip gear and sheeting system, why fork out another £3,400 for a hydraulic retarder? Manufacturers say it can reduce wear and tear on the vehicle brakes, suspension and chassis, leaving your service brakes cool should you need them in a hurry.
The cost of two vehicle drum sets and brake relines would just about cover the initial outlay, but that might be a couple of years down the line.
Some operators might even prefer a nine-speed gearbox with the 360hp P124C 8x4 which saves £1,000.
How it works
Scania's retarder is designed to control speed down long, steep grades. It links to the foot brake, exhaust brake and speed control through an ECU.
There's a five-position lever on the dash with speedselect button and auto switch near the exhaust brake on-switch.
The retarder unit on the gearbox houses a rotor and two vaned stator rings; once fluid is released between them braking begins and as fluid pressure rises so does the braking effort.
Heat generated in the system is dissipated via a heat exchanger in the cooling system.
Used manually the dash lever slows the tipper to the required speed, but remember that you need at least 1,700rpm for optimum retarder and exhaust brake performance. Press the end button and the tipper maintains that speed until you accelerate or use the lever.
In auto mode the brake pedal brings the downhill speed control into use and the harder you press the more the retarder comes into play. Accelerate and it immediately disengages.
On the road
To assess the retarder's effectiveness in a Scania eight-legger we first drove a standard 340hp (250kW) P114C 32-tonner around Milton Keynes; an area devoid of steep hills but plagued with roundabouts, especially along dual-carriageways. Fast approaches, fairly rapid braking and careful gearchanges are needed to ensure good safe journey times.
Our basic 8x4 had a GR900 range-change gearbox with a four-on-four pattern and two crawlers. The exhaust brake operated efficiently enough, as long as the engine was spinning above 1,700rpm, but for the most part the service brakes were kept rather busy, and coped well.
Our retarder-equipped 8x4 came from the Cameron service dealership in Skipton. The 360hp P124C demonstrator with a GRS900 14-speed range change splitter box was under evaluation by Giggleswick owner-driver Kath Peacock who hauls limestone rock out of a neatly landscaped quarry near Ingleton,
deep in the Yorkshire Dales Equipped with a WBS insulated body, Edbro front end gear and Dawbarn rollover sheet, the 360hp P124 is kept busy delivering 23.5-tonne loads of aggregate to a council yard which is some 25 miles away.
Our journey began with a short twisting descent to the main Skipton-Kendal road. With 5L engaged and the engine singing at around 1,850rpm the dash mounted lever check-braked the tipper at a safe speed with consumate ease. It worked equally well on the long drag past Settle, with the retarder pegging the Scania at the 40mph speed limit with lever control or by dabbing the brake pedal.
There's no doubt the retarder enhances the Scania's braking performance.
This cab is already quiet and comfortable; with such an effec tive auxiliary brake tipper driving becomes almost leisurely whatever the terrain or weather. It's certainly easy on the driver and if, as the makers claim, it saves on vehicle wear and tear then so much the better.
Cameron senses a lot of interest from Dales-based hauliers; it has already sold six to the local Pennine Bulk Transport fleet.
All that's needed now is some sort of financial incentive from the Department of Transport...but don't hold your breath.