Potteries Motor Traction
1958
AEC Reliance 470
Willowbrook C41F

PMT had five of these coaches plus one similar acquisition on a Leyland Tiger Cub chassis from the takeover of Dawsons, Ash Bank. They suffered as always with AH470 engines with cylinder head gasket and wet liner seal failures. This is why this photo was taken adjacent to Llandrindod Wells Railway Station on a summer evening in June 1971. A similar Reliance had taken a party of Scouts on a weeks expedition to Tenby and inevitably the engine had failed in South Wales. I was summoned at short notice to take a replacement vehicle arriving at South Wales Transport Ravenhill Depot shortly before midnight. I chose the scenic route rather than the M6/M5 as I didn’t fancy becoming another engine failure casualty at the side of the Motorway. During 1971 and 1972 three of these Reliances were modified for one man operation and repainted in bus livery. The conversion included jack knife doors the motor for which would only fit in the space occupied by the nearside front passenger seat hence reducing the capacity to 39. As the vehicles were 13/14 years old by this time one wonders if it was really worth the effort. I recall 762 which was allocated to Biddulph Depot put in some quite respectable mileages as an omo saloon.

Photograph and Copy contributed by Ian Wild

16/11/14 – 09:44

An odd design which seems to transition from the early 1950s at the front to the late 1950s at the rear.

Phil Blinkhorn

16/11/14 – 11:21

Northern General had a batch of very similar C37F Willowbrook Viking coaches on an AEC Reliance 2MU3RV chassis, so as I understand it, they would have had the larger AH590 engine. Delivered in 1959, they were JCN 445 to 454, numbered 1845 to 1854. About 1967, it was decided to convert them for use as OPO vehicles, but the changes were far more radical. I don’t know if the conversion was carried out ‘in-house’ or whether they went back to Willowbrook to be done, but the whole front end was chopped off, and a new service front grafted on, I believe they were also up-seated to 41. Here is an example of the end result, I believe they remained in service until around 1975

Ronnie Hoye

16/11/14 – 18:03

Were the gasket/liner problems eventually cured by AEC?

Chris Hebbron

17/11/14 – 06:47

In a word, Chris – No! AEC’s involvement with wet liners began in 1935 with the introduction of the ‘6.6’ A172 engine (actually of 6.75 litres) in the lightweight Regal II. This engine proved to be decidedly troublesome, and the wet liner problems were carried through into its postwar ranges developed from about 1953. In the end, AEC reverted to dry liners in the AV/AH 505/691/760 engines. By contrast, Dennis employed wet liners in its ‘Big 4’ petrol and O4/O6 diesels from the mid 1930s onwards, and all were generally free of the troubles that plagued the AEC efforts.

Roger Cox

17/11/14 – 06:47

2MU3RV was still the AH470, Ronnie – 2U3RA was the AH590. Both of these had wet liners and gasket head problems. The AH691 and AH760 were new dry liner engines which did not have the same problems. Sadly the reputation was tarnished and many did not return to AEC. Also, like the later Leyland Panther, others persevered and overcame the problems.

David Oldfield

17/11/14 – 09:51

Thx, Roger. It’s amazing, from what you say, that folk continued to buy AEC’s with these engines, if they were so troublesome, although I admit that post-war distress purchasing would retain undeserved loyalty to a large extent. Were LTE’s engines of this type? I’ve never heard of problems with those Incidentally, did AEC/Leyland ever offer ‘outside’ engine options at ordering stage, such as Gardner? I’ve never heard of any, but who knows?
David O, strange that, following on with gasket/wet liner problems, which existed for decades, AEC cured Crossley’s engine breathing problem within months!

Chris Hebbron

17/11/14 – 11:37

The AV (vertical) engines never suffered to the same extent as the horizontal AH engines and substantially LTE had no problems with RMs (once the teething problems were ironed out) – including the AV590. Neither did Sheffield with its Regent Vs and Bridgemasters. [In passing, the AV version of the AH691 was actually a wet-liner and really an "out-boring" of the AV590.] It is surprising that they carried on so long before they eventually reverted to dry-liners – and as I said lost friends along the way. Those who stayed were rewarded by the AH691/760. AEC were not alone in having problems with putting an engine on its side. I am a "fan" of the O.600/O.680 – but this was not without its problems either – as Stephen Barber has alluded to in his Wallace Arnold Books. Conversely, there was enough faith in the later AEC engines to offer them, initially, as an option, in Series 2 REs and VRTs. The famous Werner Heubeck at Citybus who force BL to continue the RE for Northern Ireland was known to be very interested in an AH691 RE but BL back out at the last minute and cancelled the option – much to Heubeck’s anger. [Something similar is thought to have happened with the VRT – when someone showed interest, the option was withdrawn.] As for Gardners, there were the famous Rochdale D2RAG Regent Vs and the less famous Glasgow and Aberdeen D2RVG Regent Vs.

David Oldfield

17/11/14 – 16:50

Huddersfield JOC took delivery of 16 Regent’s and 37 Regal’s with 6LW engines between 1935 and 1939.

Eric Bawden

17/11/14 – 17:19

Forgot those, Eric. Crossley engines were another, and simpler, matter. AEC basically knew the problem – Crossley refused to pay royalties to Saurer and so mangle the design of the piston/cylinder head to make it different. AEC simply came up with a design which solved the problem without infringing the rights of Saurer. [I’m not an engineer, so I cannot elucidate.]

David Oldfield

18/11/14 – 06:23

As I have always understood it, the bored out 11.3 litre version of the AEC AV590 wet liner engine was the AV690, which was introduced at the same time in 1958. It was most commonly employed in commercial vehicle models such as the Mammoth Major V and in many export PSV’s, but was optional in the 2D version of the Regent V, and in horizontal AH690 form in the 2U and 4U larger Reliances, though it was not differentiated in the model designation.
The AV/AH691 was the 11.3 litre dry liner engine which was announced in late 1964 at the same time as its smaller equivalent the AV/AH505. The AV691 was then offered as an option in the Regent V and Renown, models, which were then designated Regent 691 (prefixed 3D) and Renown 691 (prefixed 4B) though none of the latter were built.

John Stringer

18/11/14 – 06:23

David, the wet liner 11.3 litre was the AV/AH 690. The 691 was a dry liner in vertical and horizontal formats. Even the switch to dry liners did not resolve AEC’s engine reputation. The AV/AH 505 in particular soon revealed weaknesses in service. A cover plate was fitted on the top of the block under the cylinder head, and this plate was held in place by a number of set screws. The inevitable expansion and contraction of this component in service caused the screws to fail, leaving a hole that allowed coolant to escape. This, if not spotted and remedied, could result in a seized engine. The design defects were progressively eliminated, but AEC’s reputation as an engine builder was not enhanced.

Roger Cox

18/11/14 – 06:24

Ronnie – that’s a proper bus conversion done by Northern, however as they were done in 1967 they would operate for quite a few years to get the money back. We only started conversions in 1971 and as I said, perhaps a bit late in the day – but don’t forget PMT had the largest fleet of Roadliners in the world and anything had to be tried to mitigate the chronic unreliability.

Ian Wild

18/11/14 – 06:25

Chris, for a short period in 1956/7 the AEC Regent V was offered with the option of a Gardner 5LW or 6LW engine. There were only three takers; Glasgow and Dundee Corporations bought examples with vacuum brakes and spring operated preselector gearboxes (model D2RV6G,) and Rochdale Corporation had examples with air brakes and air operated preselector or semi-automatic gearboxes, model D2RA6G. The Rochdale examples were described in my article on this site.

Don McKeown

18/11/14 – 10:19

The prototype Crossley HOE7 engine design came about when the firm’s engine designer, W.C. Worrall wwas diagnosed with tuberculosis prior to the outbreak of WW2. He was sent to Switzerland to recuperate, and, whilst there, visited the Saurer factory, where he himself had once worked. Saurer gave him permission to use the company’s advanced four valve head and toroidal piston cavity in his new engine design. Shortly after Worral’s return to Britain, war broke out, limiting Crossley’s commercial options, but three prototype engines were constructed with combustion chamber detailed design being made by Leslie Bennett, a mathematician and combustion specialist. Thus Crossley had done all the right things and succeeded in a designing a powerful and reliable unit. Then, as the new SD/DD42 chassis production began to get under way in 1944, Saurer, entirely reasonably, asked for a royalty or licence payment in recognition of the fact that the Swiss company’s patents were employed in the head design. The exact details of the fees involved have since been buried in the passage of time (probably deliberately). The Crossley MD, Arthur Hubble was having none of this, and refused to comply, instead ordering that the cylinder head of the new engine be redesigned completely to avoid any payment to Saurer. The new head had two valves per cylinder instead of four, and the toroidal piston cavity was reshaped with sharp concentric ridges, the (misplaced) theory being that these would improve the swirl effect. The new head was married up with the original block intended for the Saurer type head, and the result was a motor strangulated by hopelessly contorted airflows. In addition, poor coolant circulation led to overheating and high back pressure in the crankcase. This ill advised redesign ended the involvement of Saurer, but left Crossley with a exceptionally poor engine. When AEC took control of Crossley, it lost patience with Gorton’s refusal to attend to the cylinder head deficiencies and undertook remedial design itself. It is an overstatement to suggest that AEC simply solved the problems with the Crossley engine. The downdraught cylinder head was not a cheap conversion, and, although it did improve the airflow characteristics and reliability issues to a very great extent, the HOE7 could never be turned into a truly good motor. What baffles me somewhat is the fact that Dennis used a four valve head and toroidal piston cavity in its O4 and O6 diesels, yet no payment was ever made to Saurer. Presumably the Dennis design differed sufficiently to escape the Saurer patents.

Roger Cox

18/11/14 – 15:50

Aberdeen Corporation did have five Gardner engined AEC Regent V’s with Crossley bodies (205 – 209). In 1959 they purchased five AEC Regent V’s with AEC engines and Alexander bodies (271-275). By 1963, they also had been fitted with Gardner 6LW engines.
I seem to recall that Maidstone and District also converted some coaches in the same manner as that done by Northern General.

Stephen Bloomfield

19/11/14 – 05:57

Stephen, I think the Maidstone vehicles you refer to had Harrington bodies but the end result was quite similar.

Ian Wild

24/11/14 – 17:03

On the subject of seized AEC Reliance engines I Drove for Stanley Gath Coaches of Dewsbury in the late 1970s. Due to a vehicle shortage one weekend a AEC Reliance/Plaxton was hired from Kirby Coach dealers of Sheffield. Returning from Blackpool on the Saturday night the engine seized up on the M62. Rather then owning up to this, a visit was made to a scrappers at Barnsley and a similar engine was obtained and shoe horned in. I dare say no one was ever the wiser.

Philip Carlton

25/11/14 – 06:31

Thx, folks, for the answers to my queries.

Chris Hebbron

Wakefields Motors
1948
AEC Regent II
Weymann H30/26R

Having completed its journey, 156 is seen here turning round at Whitley Bay Bandstand before returning to North Shields Ferry Landing. The service 8 was known to crews as ‘the track’ because it followed the exact route of the Tynemouth and District trams. The AEC Regent II chassis was well built, rugged and reliable, and was available in two options, take it or leave it. The engine was a 7.7 litre diesel, and the transmission was a 4-speed sliding mesh gearbox with friction clutch. It was an entirely different matter when it came to choice of body. NGT Percy Main depot opted for the H30/26R Weymann. This is one of twenty nine of the type delivered to them between 1947 & 48; the 1947 intake were FT 5698 to 5712, 128/142, and 1948 were FT 6143 to 6156; 143/156; they were all ‘Tynemouth’ apart from 141 – 142 & 156 which carried the Wakefields name. The first vehicles to carry this style of livery layout were the 1958 Orion bodied PD3/4’s, so the photo is after that date, but just look at the collection of coaches in the background.

Photograph and Copy contributed by Ronnie Hoye

10/11/14 – 06:58

Good to see a Regent II. I used to take them for granted in Reading, where they were the mainstay of the motorbus fleet from 1947 to 64, but they seem rare today. Was the choice of 5 bays a matter of date, of chassis design or of operator’s choice?

Ian T

10/11/14 – 08:23

According to "Weymann Part 2", these were delivered (due to shortages) without destination blinds and with metal panelling covering the "empty holes".

David Oldfield

10/11/14 – 11:47

I think that the matter of 4- or 5-bay bodywork is a matter of date. The 5-bay was standard in the immediate post-war years, on AEC and other makes. I am fairly sure I read somewhere that Weymann re-designed the body as four-bay for the AEC Regent III chassis, but did not build it on other makes/types, at least initially. Perhaps those with access to the "Weymann Part 2" book will find some detail, as my memory may be in "error mode" on this one.

Michael Hampton

10/11/14 – 13:31

Michael, I don’t know when the change came about, but Percy Main’s 1952 Guy Arab III’s ‘FT 7381/90 – 181/90 were four bay type. They were also P/M’s first 8ft wide D/D’s, and the first with sliding cab doors.

Ronnie Hoye

10/11/14 – 13:32

I think, originally, that AEC and the body-builders colluded to make a four bay body – but it relied on body fixing points. Guy and then Leyland eventually caught up by building chassis with compatible points and then Daimler. [Bristol was obviously a different case.] What was more interesting was the reversion to five short bays with the appalling early Orions.

David Oldfield

14/11/14 – 14:56

What was the difference between a Regent II & III’s. We had Regent III’s in Sheffield around the same year. They had pre selector gearboxes though.

Andy Fisher

15/11/14 – 05:41

AEC Regent. Mark I, II and III.
AEC Regent 661 petrol engine was built from 1929-1942, powered by an AEC A145 7.4 litre engine, many of the early examples had the open staircase later enclosed and the typical 30 seats over 26 seat layout became the standard design on a 27 foot long by 7 feet 6 inch wide chassis with over 7000 built.
AEC Regent Mk II 661/O661 was developed in the late 1930’s at 27 feet 6 inches by 7 feet 6 inches with the A173, 7.7 litre 6 cylinder diesel oil engine, resulting in the London Transport RT 1-151, the Regent II was curtailed during the second world war but recommenced after the war with only 700 built.
After the war AEC with London Passenger Transport Board had developed the AEC Regent III O961 with the more powerful AEC 9.6 litre engine. 8261 were built over the next 10 years, most of these were the iconic RT for London Transport.

Ron Mesure

15/11/14 – 05:42

The Regent II had a 7.7 litre engine, sliding mesh gearbox and vacuum brakes. The Regent III was its successor, and could be supplied with the same spec, in which case there was very little difference between the two. Most Regent IIIs however had the 9.6 litre engine, and many of these had air brakes and air-operated preselector gearboxes (especially in Yorkshire!). In this form the Regent III was a development of the London RT type which had its origins just before the war.

Peter Williamson

14/12/18 – 06:24

I have only just noticed that four years ago Ron Mesure attempted to give a fuller and more detailed answer to Andy Fisher’s question than mine. Unfortunately this is mainly incorrect.
Firstly, the petrol engines used in the Regent 661 were of 6.1 litre capacity, the 7.4 litre A145 being reserved for the three-axle Renown. Diesel engines included an 8.8 litre and a 6.6 litre unit as well as a couple of Gardners (rarely fitted).
Secondly, the version with the 7.7 litre engine was not called Regent II before the war and did not include RT1-151, which used a 9.6 litre engine like all subsequent RTs. Although designated as O661 and built before the Regent II was introduced, RT1-151 (and an odd similar chassis for Glasgow) are now regarded as the first Regent IIIs.
Thirdly, the lengths quoted are incorrect, as the maximum length of a two-axle double decker was 26 feet until 1950.

Peter Williamson

Rochdale Corporation Welfare Dept.
1949
AEC Regal III 9621E
Roe B33F

BCP 543 was originally one of twenty-two AEC Regal III 9621E’s with Roe B32R bodies delivered to the Halifax Corporation and JOC fleets in 1949, and was numbered 268. Fourteen of them, including 268, were rebuilt at Skircoat Road workshops during 1953/54 to B33F layout and with modifications made to the front bulkhead to allow for one-man-operation.  These were also for a time repainted into a livery of cream with a single orange band to draw attention to the fact that they were OMO and in connection with them being used for the local Countryside Tours during the summertime and bank holidays, though they were returned to standard bus livery later. Withdrawn in 1964, 268 was sold to the Rochdale Corporation Welfare Department who rebuilt it with a rear tail-lift for the transport of disabled people and numbered it 500. They renumbered it 900 in 1970, and it was withdrawn and sold for scrap in 1972.
Though Roe’s teak body framing always had an enviable reputation for strength and longevity, when Halifax Corporation had carried out its modifications, the cutting of an aperture in the nearside for the forward entrance directly opposite another on the offside for the emergency exit, along with the bulkhead alterations caused a significant weak spot across the bodywork at that point, and the resultant sag in frame stands out quite clearly – particularly in the offside view above. The nine Regals that retained their rear entrances remained sound until the end – which unfortunately came rather early, some going as early as 1958 and the last one in 1962. Lovely little buses.

Photograph and Copy contributed by John Stringer

21/10/14 – 06:19

Although allocated to the Rochdale Welfare Department this bus received what was then the current Rochdale Corporation bus fleet livery with the exception that the blue band was a lighter shade. This is interesting as when the new predominantly cream Rochdale bus livery was being introduced in the early 1960’s, two vehicles wore this lighter blue band for a very short period before the darker Oxford Blue trim as pioneered on AEC Regent V no.277 was adopted as the new standard. These were Daimler CVG6 no.238 and AEC Regal IV no.12. I seem to recall the light blue only lasted a matter of weeks on these vehicles before the Oxford Blue replaced it.
At the time as a schoolboy spotter I was quite excited about this new livery but once it began to replace the streamlined blue and cream across the whole fleet I came to hate it. It was bland and totally impractical for a northern industrial town where the atmosphere in those days was mucky to say the least.

Philip Halstead

22/10/14 – 07:17

The lighter blue was worn by 12 and 238, and also on delivery by new Weymann bodied Reliances 16 – 20 (3116 – 3120 DK). It didn’t last on these, of course. The blue adopted as standard was the same shade of blue as used on the much lamented "streamlined" livery.

Don McKeown

22/10/14 – 17:59

Daimler CVG6 number 238 was always easily identifiable because the rubbers holding the destination blind glasses were painted cream whereas it was usual to mask them over during repaint so they remained black. By the way 16-20 were 2116-2120 DK.

David Slater

15/11/17 – 07:17

Re rad blankets PD2 exposed rads had a plate about one foot deep but full width. It appeared to be in the middle because that was the bottom of the cooling tubes. The lower section of the rad was a dummy. Also with the blanker fitted on the outside there was a 2 to 3 inch gap to the actual tubes which would seriously reduce the warming effect. In effect as the thermostats were pre wax type generally they failed inside a year so the engines always ran cooler than the designed temperature. Even in summer

Mr Anon