Hauling bac on the hills
Page 10
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by Bryan Jarvis III Few would argue that the addition of some form of extra 'endurance' braking to a truck's standard braking system would provide considerable benefits. An improved exhaust brake, or an electromagnetic/hydrodynamic retarder, can shoulder many of the stresses normally carried by the service brakes. Such systems can extend the service life of braking components and make it easier on the driveline and suspension.
Of course, they cost more and add weight but with industry demanding higher carrying capacity, and continual pressure to improve road safety, CV users and legislators should take a serious look at the benefits of such an investment.
Prime candidates for retarders include UK carriers of hazardous goods, those running to the Continent under ADR regs and petroleum companies. Now car transporter specialist Richard Lawson is evaluating a Voith electromagnetic retarder on one of its latest Mercedes 1834 drawbar outfits.
Two years ago we drove one of Ken Longthorne's Foden eight-wheelers fitted with a Hersham Valves VPS exhaust brake (CM 1-7 Oct 1992). We concluded it was a worthy investment. Now we have dri
ven a fully laden MAN 17.372 38-tonner fitted with the latest ZF Intarder transmission brake.
The Intarder is a wear-free hydrodynamic system available on-line or retrofitted. It comprises a gear-driven rotor/stator unit with oil reservoir and oil/water heat exchanger, an ECU and a braking level selector on the steering wheel. It is side-mounted on the Ecosplit, leaving room for a ZF PTO.
Relative
Helical gearing on the output shaft drives the Intarder rotor at a speed relative to vehicle road speed. Engage it via the selector lever on the steering column and oil is immediately fed into the Intarder circuit. As it turns,the rotor vanes push oil against the stator blades, where it is deflected and pushed back against the rotor to cause resistance and slow the vehicle.
During braking the Intarder oil heats up; it is cooled via the standard cooling system. The driver can choose between two modes: normal or "Bremsomat" (speed-hold). In normal mode up to six levels of extra braking can be chosen via the operating lever: maximum braking power is 402hp (300kW).
To get an idea as to its effectiveness, CM took MAN's 38tonne demonstrator to the 10% Crinckly Hill in Gloucestershire.
Holding the 17,372 in check at around 35mph in 6H down the mile-long descent without the Intarder called for long, hard service brake applications.
As the slope lessened we simply backed off the lever to a position commensurate with a safe driving speed then released it altogether.
Once familiar with the Intarder,you can use it to slow down approaching
roundabouts or junctions so with good anticipation there's little need for heavy braking with the foot pedal.
Should you come across an unexpectedly steep drop simply apply the Intarder then select a suitably low gear in comparative safety.
The Breinsomat mode is an optional feature that enables the driver to program in the vehicle's current speed to prevent that speed from being exceeded even on long downhill runs.
Either way it cuts fuel wastage, is kinder to braking components and feels easier on both the driver and the load, Such devices may cost more at the start but payback is guaranteed over a couple of years, if only in wear on brake shoes, drums and tyres.
If the Government were to offer financial incentives for hauliers prepared to fit them, retarders would also help improve the industry's road safety record.