Coachbuilders for these chassis included Plaxton and a number of smaller concerns, Seddon also built their own coachwork for these models, mainly for export.
Although Bedford were to have success with such a layout between 1970 and 1987 the marks 10 and 11 sold poorly, with Seddon, Charles H Roe, Duple and Plaxton bodies on the few known examples.
A sole mark 19 using many AEC Reliance components in a Seddon-sourced frame with Harrington body being sold in 1960 to Creamline Coaches in Hampshire.
But following the success of the Ford R series and the Bedford VAL and VAM, Seddon decided to make a similar product, to a variety of wheelbases with Perkins engines; as on the competitors, these were vertically mounted on the front platform.
[5] A rear-engined derivative was the Mark 5 (only one sold in the UK, a 45-seat Van Hool coach) and a version with a turbocharged Perkins 6-cylinder engine mounted at the front but under the passenger floor was the Pennine 6.
The market leader was in the rear-engine single-deck segment was the Bristol RE and Seddon decided to use similar mechanical units, notably Gardner engines and Self-Changing Gears semi-automatic transmission.
Seddon decided to use a straight frame using 8in channel longitudinals and mainly tubular cross-members which was oriented to rise from front to rear at about 5 degrees from the horizontal.
Unlike the RE and the Leyland Panther the radiator was not carried at the front but hung from the offside of the chassis in mid-wheelbase, ahead of the rear axle.
In the event three other makes of bodies were fitted to the RU, Plaxton used a steel-reinforced hardwood structure whilst East Lancashire Coachbuilders and Charles H Roe both used steel-tube framing.
It was exhibited at the 1970 Commercial Motor show at Earls Court in the livery of Crosville where it was overshadowed by the debuts of the Leyland National and the Metro-Scania;[7] it was then registered ABU451J and served as a demonstrator across Great Britain.
[8] Initial list prices complete with body started at £6,200 which was substantially cheaper than an equivalent ECW-bodied RE,[9] lead times were very good because Seddon had expanded into adjacent premises in order to set up a dedicated bus-production facility.
Production ceased in March 1974 after 274 were completed,[10] the last chassis numerically were numbers 56041/2[11] which were ordered by Huddersfield and delivered to West Yorkshire PTE in September and October 1974 respectively (registered PVH 452/453M).
Subsequently LUT (and other outliers such as the Calderdale Region of West Yorkshire PTE) were prevailed upon to take the standard version of the Derwent II.
[18] Seddon started delivering this (joint) record order for complete buses in April 1971 with 46 delivered with J plates (i.e. prior to August) and completed it just over a year later in May 1972, a creditable performance for a new factory unit which was also engaged in a batch of 100 Perkins V8-engined Pennine 4 for Kowloon Motor Bus and a large number of smaller orders, as well as converting double-deck buses to dual-door for such undertakings as Merseyside PTE and Nottingham City Transport.
The Silent Rider project alone cost £100,000 at mid-1970s values, promotional tours to Sheffield and Chicago, Illinois, United States may have been prestigious for the Executive and for the manufacturers of vehicle and batteries, who were both major employers of voters in the PTE area,[19] but Cook County Transit and the South Yorkshire PTE were, lacking the electrical-charging and cell-care infrastructure installed in a Manchester garage as part of the project, able to get even less use out of the thing than Greater Manchester who tried to employ its advertised 100-mile range by using it sporadically on one morning and one afternoon peak-time journey on routes 202/3.
[20] These were specified for limited-stop 'trans-pennine' services and in the year after delivery became the 'top-shed' buses for Calderdale JOC (which was a merger in 1971 of Halifax, Todmorden and National Bus Company interests.)
When West Yorkshire PTE was formed all three Calderdale RU were moved to Huddersfield, concentrating the fleet's collection of the type in one place.
It was an ungainly vehicle with a high ramped floor, carrying 39 Plaxton seats, all forward-facing, Large curved side screens were used on the four main-bays, of a type used on contemporary Mercedes-Benz and Neoplan coaches leading to a parabolic roof contour, but aft of the rear axle flat Willowbrook-pattern bus glazing was used, offside and nearside emergency doors were fitted.
It seems an irony that two early Harrington Cavaliers were exclusively to transport the blind yet this coach, finished in navy blue with scarlet flashes, was able to assault the senses of the sighted for one of the longer operational lives of its type, actually outlasting the two similar bodies Widnes/Halton had on Leopards.
The air cleaner was located aft of the nearside rear wheel and although this was hard to reach had to be attended-to regularly if engine performance was not to suffer.
'[28] The Pennine bodies were found to be rather too light and tended to crack around the chassis mounting points, whilst the dual-door versions also had localised fractures around the centre exit door.
Again referring to the unlikelihood of pulling up in a straight line, he also recalled the first batch had car-type handbrake levers which disintegrated in use; later upon becoming a fitter he discovered that the brake adjusters (of two different sorts on the different batches) were virtually inaccessible, that spring shackle-pins often needed to be knocked out which was equally difficult, that topping up the fluid flywheel was "nigh-on impossible" and only done when a bus developed gearbox-slip, and that in order to remove the engines for overhaul, Doncaster engineers actually had to cut-away the rear cross member and bolt in a removable piece of girder once they had done.
Even though, as pictured, the offside fog lamp of this bus is missing and there is a prominent fracture-line in adjacent regions of the front fibreglass panel.
[11] Crosville had all of its 36 ft models converted with a revised engine and gearbox mounting closer to the rear cross member, allowing a longer universal-jointed drive shaft to be put in place, this arrangement was also applied to later long-wheelbase RU as built.
Unlike their Bristol REs which were cascaded to more remote parts of the company's North Wales hinterland as newer replacements arrived, Crosville's Seddons were generally kept close to the central works at Chester.
[35] Rotherham's nine 44-seat Plaxton Derwents were its last single deckers, they entered service in late 1972, replacing 1963 AEC Reliances, and were withdrawn by SYPTE on expiry of their certificates of initial fitness.
[36] Lest it be thought the RU was unpopular with everyone, the late batch of eight 11-metre versions supplied to Darlington Transport were well liked by the operator and they tried to commission more from Seddon Atkinson after the end of production, this was not to be and Darlington (whose other single-decks were then Daimler Roadliners and Daimler Fleetlines) instead bought four dual-door Leyland Leopards in 1977, their next two new vehicle orders went to Dennis for single deck Marshall-bodied Dominators, then in 1983 they got Ward Motors Ltd to build them six RU-like vehicles called the GRXI (for Gardner, Rear-engine 11 metres.
These differed from the RU only in having 180 bhp Gardner 6HLXB engines, ZF power steering and Wadham Stringer Vanguard B45D bodies, a further six were optioned, but the Ward Brothers' company went bankrupt before these could be built.
The last RU to run as a PSV is understood to have been new to Lytham St. Annes STJ847L which was withdrawn by East End Coaches, Clydach in South Wales in late 2000.
Although the "Silent Rider", was stored for the Museum of Transport, Greater Manchester it was vandalised and found to be beyond economic restoration and reluctantly scrapped.