No relaxation now from Bathgate Engines
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id's major Scottish t has had its problems, o has the engine range b is built there but the ire is changing, as Tim Elmore reports -IISTORY of Leyland's Bathplant is similar in some to the history of the enwhich are built there. Both )ther unhappy. At one time e mid-1970s as many as 0 Leyland employees 3d at Bathgate. Now there ily 2,000.
rhaps understandably, Iver, Leyland management
d prefer not to dwell on the led past of its major Scotplant, and points instead some optimism to what the 3 holds.
air hopes are resting on nd/Cummins collaborative ament which was signed a over one year ago. It will to fruition in early 1986, the first Family 1 engines, gned jointly by Cummins J. I. Case and now officially B-Series by Cummins) of .0,000 which Leyland plans anufacture annually by 1990 ome out of Bathgate.
a work needed to prepare plant for its new role is ressing on schedule. Leywill be manufacturing (shafts and camshafts and in cylinder blocks and s from Cummins in the e B-Series engines which a swept volume of 0.96 per cylinder will be assemin three, four and six-cylinconfigurations and will be in Europe by Cummins to ufacturers of agricultural, ne and power plant equipt.
ropean vehicle manufacturnust also be on Cummins' )f potential customers, for B-Series engines, in 'rally aspirated, turbo-ged and charge-cooled is will have power outputs ing from 37 to 142kW (50IP).
it the major user will be Leyitself for B-Series will be the acement for the Bathgate98-Series, four and six-cyltr range. The chequered history of this product is something Leyland is now prepared to discuss because the development work which has been carried out progressively over the past three and a half years has solved all the serious 98-Series problems, Leyland believes, and resulted in an engine range which deserves a better reputation.
But why develop at all an en
gine which is so close to the end of its life? The danger from Leyland's point of view was that the 98-Series' reputation would become so bad that it would adversely affect sales of the BSeries-engined Leyland models in the future. Give a vehicle a bad name and it sticks.
Moreover, an important new Leyland vehicle, the Terrier replacement, coded MT 211, which is to be launched next year, will be fitted with 98-Series engines, and if they were then still troublesome there would be little hope of the new model doing well.
It is worth explaining at this point that Leyland's "Radical Plan" of 1981 split Leyland Trucks into seven autonomous "business units" making Bathgate Engines effectively a supplier to Leyland Vehicle Asse m b I y, for example, and therefore subject in theory to the usual pressures a customer puts on his suppliers. The other five Leyland "business units" incidentally are Vehicle Assembly Bathgate, Albion (Scotstoun), Leyland Engines, the Foundry and Scammell. The "98" in the Leyland engine designation refers to the bore diameter, in millimetres. The original Leyland engines of this type had a bore of 95mm which was later increased to 100mm, then reduced to 98mm, though nobody at Bathgate is quite sure why.
The in-service problems with the engine really began to increase as the rated power and speed went up for commercial vehicle applications (in agricultural tractors, the 98-Series was much less troublesome) — now is that not a familiar story?
The most significant problems were crankshaft failures; connecting rod shank fracture; high oil consumption at low mileage; inlet valve seat burning; severe cavitation erosion of the cylinder liners; and excessive oil and water leaks.
The man who was given the unenviable task of finding solutions to these problems was Bill Stewart, power units project executive at Bathgate Engines. With remarkable modesty, he says that "all the means of solving the problems were already readily available. I simply began to apply them."
His approach was as methodical as you would expect from an engineer with his experience — 22 years with Perkins before joining Leyland six years ago.
The main reason for the crankshaft failures was identified as being "inadequate support from the main bearing caps due to ineffective clamping".
The strength of the shafts was increased by minimising the need for cold straightening and increasing the hardness range but the major "fix" which was introduced in January 1980 was to change main bearing cap clamping from studs to bolts (as shown in the accompanying section diagram).
A further benefit of this modification was that now the highly stressed threads in the cylinder block were in a "meatier" area. Bill Stewart says that the main cause of the unacceptably high incidence of connecting rod shank failures was relaxation of the rod to cap fixing which allowed fretting between the cap and rod, but it was also noticed that some of the failed components had fine pieces of metal, almost certainly from the thimble dowels, between the faces, which would have prevented correct clamping in the first place.
"Dealing with the swarf was easy", said Bill Stewart, "we simply put in chamfers to trap it."
Clamping was also improved by using new Unbrako bolts which were rolled after heat treatment and by increasing the clamping load through a higher tightening torque. The conn rod's shank section was strengthened by reducing the depth of the bolt holes. April 1980 was when the connecting rod "fix" was completed.
The way Leyland dealt with the problem of high oil consumption on its 98-Series engines can be divided into two areas: piston, ring and cylinder development; and inlet valve and port development. The details of these developments really warrant a separate description of their own, as indeed does the Leyland study, conducted with help from Edinburgh University, into cylinder liner cavitation erosion, but they can be very briefly summarised thus.
A plateau-honed finish was adopted for the cylinder liners in November 1980 and Wellworthy controlled expansion pistons were introduced (the first time Leyland had used pistons of this type) in April 1981. Apart from helping to reduce oil consumption these component changes also pleased Tom Flanigan, production manager at Bathgate Engines, because they led to a lower component count. Three types of cylinder liner and two types of connecting rod were replaced by one type of each for the entire 98-Series range.
Even greater compon rationalisation resulted from Stewart's redesign of the valve and port. The old typ valve which was masked t( duce swirl in the incominc charge had to be prevented rotating and the means of d this, a key in the valve s was, in Bill Stewart's w, "costly and complicated".
The latest cylinder hE which was introduced in ruary 1981, has a mild hE : in its inlet port to induce I and therefore does not I a masked valve. The redeed valve guides are corn] to inlet and exhaust valves give much better control • oil flow.
further refinement to the e train was introduced in 1982 when chrome flashing first used for 98-Series valve is, and stem tip caps were d to overcome end face gutig and Brinelling, and to en-age valve rotation.
le controlled expansion piswas part of the solution to land's cavitation erosion )lem. It improved piston iility and reduced slap by reing piston/cylinder clearance er part-load conditions. The of the solution came from a ? cylinder liner with uninly thick wall and from the Dduction of a Fleetguard lant inhibitor in April last r.
y comparison with these Dlems, those of odd oil leaks occasional leaks from the inder head gasket might m relatively minor, but they received equally painstaking attention from Bill Stewart and his team. I hope to describe these measures separately in a later feature.
Because all these improvements have been introduced progressively it is by no means easy to quantify the effect they have had. But if anybody is in a position to do so it is John McKay, quality manager at Bathgate Engines. He is the man whose ear is bent by any dissatisfied customers, especially Bathgate's biggest customer the Leyland Assembly Plant, when his engines go wrong.
Like any engine manufacturer, Leyland is rather reluctant to publish detailed warranty and defect statistics but John McKay showed me figures which indicated a 77 per cent reduction in "defects" (and that term means any fault, however minor) on 98Series engines delivered to Leyland between September last year and this year.
I was also told warranty claims had been reduced by 25 per cent over a rolling twelve month period.
Whether or not these figures impress you, one thing is clear — Leyland now has a renewed confidence in its 98-Series engines. It looks as though its twilight years might be its happiest.