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Road speed governors —part of economy package

25th July 1975, Page 46
25th July 1975
Page 46
Page 46, 25th July 1975 — Road speed governors —part of economy package
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Which of the following most accurately describes the problem?

iE AUTHOR of a test report attic wind drag trial shows el savings possible at speed" !IL/ February 7) made a par:Warty pertinent comment garding drivers' response to ad speed limitation on motorys Fuel consumptions were [-fleased at steady speeds at .the otor Industry Researdi Assoation's proving ground using ro identical Golden Wonder rd/York boxvan artice and it es shown that an Airshield flector could reduce fuel bills r 10 per cent. In a paragraph lating to consumptions at eady speeds of 64 and 801on/h O and 50mph) the author of Le article observed: " The 641crit/h run was repsentative of traffic-free-Aerad ms while the 80Ian/h test was mskiered to be typical of ;otorway working where drivers re diligent enough to hold 3wn their speeds to a predeterined level in the interest of et economy. Just how realiatic tch a oomparison is will vary ern one fleet to another."

Equipping a vehicle with an r-drag reducer also increases s maximum speed potential at igine rpm below the governed wed and this is a worrying msideration to some potential ;ens of deflectors, notably in ie case of vehicles having a gh power-to-weight ratio and high top gear. And as menoiled by an operator of a barge fixed fleet which includes hightwered matimum-Ioad attics nployed on motorway runs, it one of a number of ways hick can be used to reduce Nag or improve power utilize

mbitious

These include application of thermostatically controlled fan id/or radiator shutters, loweig tyres and low-viscosity brioants as well as a high axle t.tio; and, more ambitiously, :onomy measures could include edification of the engine taracteristic to increase torque • efficiency over part of the ad/speed curve.

This operator is, however, thappy about the value in ectice of spending money on 1 economy package unless aximum vehicle speed can be controlled. He has vehicles in his fleet capable of more than 1131.meth (70mph) and although he would favour a governed speed of 891an/h (55triph) he might be willing to consider a maxanum somewhat in excess of 971ern/h (60mph) in some applications as a concession to drivers who would resent being passed on motorways by less powerful vehicles travelling at permitted speeds.

A leading vehicle maker is known to be developing an economy package for highpowered trucks; and I gather the package will uinude a road speed governor, Ford says it is monitoring governor developments and will submit any instrument for which there is a demand to approval tests.

Associated Engineering Developments Ltd, Cawston, Rugby, is developing an electronic roadspeed regulator in close collaboration with a number of large fleet owners to obtain practical experience of Its functioning in a wide variety of operating conditions, Interest in the development would seem to be indicative of a widespread and growing awareness of the benefits of controlling maximum speed. The company is hastening slowly With development and the instrument will not be available In production form for a donsiderable time.

Cruise control

Incorporating a number of electronic components used in the company's Econocruise cruise-control unit designed for applications to the petrol engines of more powerful cars (a version cif which could be produced for equipping diesel-engined vehicles) the governor is claimed to have an advantage over eatahliahed American types in that it has 'set point accuracy" derived from negligible hyatereels and a long life derived from the absence of mechanical contacts. It is accurate to within phis or minus 0.311an/h (0.5mph) and elimination of excessive latitude ensures that the governor does not cut in at a lowerthan-rated 'speed which could embarrass the vehicle driver and possibly create a hazard.

In cormnents on the claim of some drivers that loss of acceleration at a critical moment could impair safety a technician Of the company has asked the thetbeical question : "How fast can a 32-tonner accelerate front 55mph even if it has a highpowered engine?"

Bass Production Ltd is one of the companies Which is trying Out the AE regulator and Roger Denniss the group fleet engineer is "very enthusiastic" about the potential of the governor. A Scanunell tractive unit powered by a Leyland 680 diesel was equipped by the company With a governor of American origin (supplied by AE) in 1971 which reduced the top speed of the vehicle from 105ktn/h (65mph) to 921tan/h (57triph) and provided a reduction in fuel consumption of around 10 per cent; and regulators were fitted 'to two other vehicles early on with comparable results.

Steady running

An AE prototype regulator was recently installed in a medium-powered tractive unit for a trial period and a rigid is currently being fitted with one. A tractive unit equipped with an air-drag reducer has also been run experimentally and a worthwhile reduction in fuel consumption ;obtained. Retire experiments will include operating the two types of vehicles with one or other of the two devices and with both. Further details will be available in due course.

It is claimed that an Econce cruise reduces petrol consumption party because variations of throttle opening are eliminated during steady speed running when it is operative, a foot on a pedal being rarely motionless for any length of time whatever the intentions of the driver. The device enab,les any attainable vehicle speed to be maintained under all conditions, given sufficient power, without pedal action, application of the service brake restoring the system to normal control.

A " foot saver" is perhaps more badly needed on a heavy commercial vehicle than it is on a car and the possibility that oibviating pedal fluctuations for a major pert of the motorway or trunking run might be worth investigating.

A commercial vehicle manufacturer has said that a demand for road-speed regulators might well popularise the application of regulator/Econocruise units. It is said that propping open the accelerator pedal of heavy commercial vehicles on long climbs is a fairly regular practice.

Tags

People: Roger Denniss
Locations: York

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