New box of tricks
Page 26
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THERE were plenty of new and some improved tricks announced when CAV's Northern staff got together at their recent conference, among them the news that CAV is now to compete more strenuously with other manufacturers in the product service market (CM, April 14) and the claim that the Dynair fan system, which it is now marketing, can save 10 per cent and more on fuel.
Using an example of a 13ton gvw truck operating over a 50,000 mile year, on the basis of a 10 per cent fuel saving, the Dynair fan saved £286 a year, and £1,280 over the fan's design life of 250,000 miles. These figures, based on a light vehicle, underestimated the saving with a larger vehicle, writes John Darker.
Seven-day, round-the-clock operation was enabling heavy vehicles to run for up to 200,000 miles a year, said D. W. Hiett, and operators in this class were looking for 500,000 miles without major failure.
Mr Hiett estimated that something like 100,000 shortterm rental vehicles were now operating in Britain. CAV believed that the diesel engine looked set to remain the standard commercial power plant right through to the next century, although electric delivery vehicles could well take over in the up to 2-ton payload category.
Now an entirely new design of automatic transmission control has been introduced by CAV (type 511). It is smaller and lighter, has improved electronics with integrated circuits, and the capability of up to five speed closeor wide-ratio gearboxes and the option of starting in first or second gear for a five-speed gearbox.
CAV was developingtransmission controls for use outside the psv industry, in couding an electromechanical gear shift device and its attendant gear change 'switch for use on synchromesh layshaft gearboxes. A special feature pro vided a signal back to the gear change switch lever, indicating the position of the gearbox selector mechanism. This promotes a response or "feel" to the driver similar to that experienced with a conventional gear change stick as it travels through the nuetral location.
Alternator capacity was showing a trend to greater power requirements, particularly for psvs. The trend meant that the 7in alternator was no longer adequate and CAV had been encouraged to develop air-cooled versions of the AC203, incorporating a regulator, and with versions up to 160 Amps at 24V.
Dr A. Waring, chief pump engineer, told the conference about the Maximec, a new CAV large in-line pump conceived in anticipation of legislation on noise and emission control. It would have the capability for meeting engine duties as high as 75 kW per cylinder and 1000 bars injection pressure. The Maximec's rigid cambox contributed to reduced noise levels. A life of at least 10,000 hours, or 250,000 miles between major overhauls, is obtained when full load and full speed conditions apply for 10 per cent of the total time.
The BC 50 Boost Control, a new design, was suitable for use over the whole range of equipment. As more and more engines were turbocharged, this unit would become much more a standard item.
P. Howes noted that several manufacturers were turning to belts instead of gears for camshaft and pump drives. CAV had incorporated two plain bearings in the DPA rotary pump, to take side loads, the drive to the rotor being taken via a spline shaft. He revealed that CAV was introducing a manually-operated start advance device, to advance timing under cranking conditions to ensure not only a better start but one with less white smoke.
D. J. Coe of Marketing said CAV aimed to hold spares of most applications for up to 30 years after vehicles went out of production. The company stocked all items which were requested more than three times per year worldwide. (CAV has a network of 4500 agents and sub-agents worldwide.
Mr Coe stressed that dirt, more than anything else, inflated operators' repair bills. Abrasive particles within fuel came in a variety of sizes, but the critical sizes were those less than 15 microns in diameter. An incorrectly designed filter element would allow up to 90 per cent of these particles to pass and these particles, if not removed, would shorten pump life to a matter of weeks rather than years.
The roll type of filter was much to be preferred to the star type for the roll type contained twice as much paper per element. Terry Goldrick, FTA chief engineer, asked whether CAV's pumps could be made tamper-proof. Dr Waring said some sectors of the industry wanted this but other sect liked their mechanics to able to adjust pump settin There would be no difficult3 supplying tamper-prc pumps.
The poor starting of Leyla Leopard vehicles was mE tioned by one operator. A CI spokesman agreed there Ii been problems during t winter. Service conversi equipment to correct ti would be available shortly.
Mr Goldrick (FTA) sug ested that a number of Ci agents could not service inji tors to the high standar necessary, arid the stress h on replacement packs — t "Z packs" — seemed to cc firm this.
Mr Coe said operators h the choice of factory recon, tioned units or using CA agents. "We accept th standards will rise rapidly a CAV is now agreeing mo rigorous standards wi agents. Injectors are becomil more precise and it may n make sense for much long for them to be recondition' locally."
Several large bus operate queried the need for altern tors with such a high output 100A. A. K. Allan of Ele trical Equipment, said high capacity models were mw sought by Continental oper tors. A bus operator inte jected: "We've just fought c a claim by drivers for electr cab heaters! You're not hE ping us; we'll be left with mar problems if the gear does m work, especially on loc. psv Operations."
Fanbelt failures with Dyi air fans fitted to Bedfor vehicles were queried by road haulage operator. He whtold that the maximum torqt that could be applied only ju: exceeded the fan belt capacit: Possibly the trouble lay i overtightening of bolts on th pump.
Jim Penman, an Aberdee operator, asked why HolsE equipment used on two typE of vehicles should vary whe the same maintenance wa given. He was told that nor Holset equipment was les reliable. The aim of CAV wa to make the design life of a equipment adequate. Oil suc ply and filtration might b factors.