Seddon Pennine 7

Seddon Pennine 7
A Seddon Pennine 7 with Alexander Y Type bodywork in the fleet of Stevensons of Uttoxeter
Overview
Manufacturer	Seddon Atkinson
Body and chassis
Doors	1 door
Floor type	Step entrance
Powertrain
Engine	Gardner 6HLXB 6-cylinder horizontal diesel engine
Transmission	ZF synchromesh 4 or 6 speeds or Self-Changing Gears direct-acting air operated semi-automatic epicyclic, electric control, 4 or 5 speeds
Dimensions
Length	36 ft (11 m) or 39 ft 4 in (11.99 m) for 42-57 seats
Chronology

The Seddon Pennine 7 was a mid-underfloor-engined single-deck bus or coach chassis built by Seddon Atkinson between 1974 and 1982.

Seddon Atkinson Ltd had risen to prominence in the UK bus and coach market in the late 1960s with the Pennine 4 front-engined lightweight chassis and then the Gardner-powered Seddon Pennine RU rear-engined bus. In 1970 Leyland announced it was to cease making the Leopard PSU3/3R, which version had a Leyland manual gearbox and the 140 bhp O600H engine. All future Leopard production was to be of models with the larger O680H engine and the Pneumocyclic semi-automatic gearbox. Scottish Bus Group were by this time the only purchaser of the old variant, they stated they would not buy semi-automatic Leopards and regarding the O680H as too thirsty tried to persuade Leyland to fit the Gardner horizontal engine in the Leopard. Leyland (having had less than full value from previous SBG specials) declined.

As a result, dismayed by the monopoly position British Leyland now enjoyed, by 1972 Scottish Bus Group had approached Seddon Atkinson; at the same time they were working with Ailsa, the Irvine-based Volvo truck importer, on a new type of double-deck underframe. Collaboration with SBG resulted in rapid development. After one prototype, production commenced with the first example bodied and delivered in October 1973; the last entered service after a run of 527 chassis in 1982.

No replacement was produced, thus Seddon's involvement with bus manufacture ended with the Pennine 7.

The Seddon Pennine 7 featured a ladder-frame chassis with channel-section longitudinals and tubular cross-members, available to either 5.6m wheelbase for 11m bodies or (from 1975) 6m wheelbase for 12m bodies. It was horizontal in elevation but only parallel in plan over the leaf-sprung front and rear axles; the nearside member was in-swept at the front to allow a wider low-entrance area, and the offside member was outswept in the wheelbase to allow ready access to the Gardner engine and its auxiliaries. The frame did not continue aft of the rear axle-mounting, collaboration with SBG's preferred supplier Walter Alexander Coachbuilders meant there was no worry about the body builder providing a strongly cantilevered rear overhang capable of supporting a capacious luggage boot, especially after Alexander's switch back (from 1967–72) to aluminium alloy body framing. Power steering was standard. The prototype (carrying a late body by Seddon's Pennine Coachcraft subsidiary) had a Self-Changing Gears semi-automatic gearbox, but production variants were initially to be fitted with a four-speed ZF synchromesh unit, coach versions having a higher ratio final drive allowing a 76 mph maximum speed, 56 mph being the designed maximum for bus versions, better acceleration and more flexible performance ensuing with the low ratio back axle.