M12140 Mk3 coach bogie trials

Mk3 coach No: M12140 was unusual in that it was chosen as a test bed for a number of different bogie types including the BT7 and the SIG bogie

BT7

The BT7 bogie was fitted with Clouth rubber primary suspension and vertical stiffness testing of the BT7 bogie was carried out in the Vehicles Lab at the RTC. The spring included a shaped mandrel and housing to give a non-linear, rising, characteristic. The spring was circular in plan view and therefore gave equal lateral and longitudinal characteristics. The BT7 springs were fitted in a pedestal configuration with no additional traction rod. They incorporated their own lift stop or would otherwise just ‘ooze’ apart. It is not clear how much inherent damping they provided or whether an additional vertical damper was fitted (or added later). What made the springs a bit impractical was that having so much rubber in shear led to a lot of vertical creep leading to a possible need for frequent re-packing dependent on the application. Needless to say they were not adopted for Mk3 coaches

Sway test

 A Mark 3 coach undergoes a sway test in the EDU sometime in the mid 1970's. It is fitted with experimental BT7 bogies with Clouth rubber primary suspension

Author's collection
T4 bogie M12140 is pictured at Manchester Piccadilly with the BT7 bogie on trial

Derek Evans
M12140  fitted with the BT7 bogie at Stafford in March 1981

Paul James

BT41 SIG bogie

It was also used to trial the SIG bogie prior to selection for the Mk4 coaches
M12140  fitted with the SIG bogie

Dave Bower
M12140  fitted with the SIG bogie

Unknown

T4 bogie

Not yet come across any photos of T4 fitted to M12140

T4 The T4 bogie pictured in Litchurch Lane works - note the International coach in the background

unknown

BT17 bogie

BT17 bogie was a BT10 but with coil/rubber pedestal primaries and was fitted under Mk3 coach No: M12093.

 

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