LT engine codes
I am grateful to Steven Wood for this chart and explanatory note.
Notes to Accompany Chart 0308 Vehicle Engine, Fuel Pump and Diff Ratio
This table provides details of engine codes used for the RT through to the DMS class.
The LT chassis code is set out in the first column with the LT engine code for each chassis sub type is given in the second column and corresponding manufacturers engine code included in the third column.
What is notable is the number of engine variants for RM vehicles. There are 7 LT codes for RM engines and these can be summarised as follows:
EN45 AV590 (early type with thick lead bronze bearings)
EN52 Leyland 0600
EN54 AV590 (later type with thin reticular tin bearings)
EN55 AV690 (fitted originally to RMs but subsequently converted back to 9.6 litre 590).
EN60 AV690 (as fitted to RCL)
EN61 AV690 (as fitted to BEA coaches rated at 175bhp @2200 rpm)
EN62 AV590 (later type with thin reticular tin bearings and DPA fuel pump and fitted to the very last batch of RMLs)
To complicate things further, there are about 10 manufacture variants of the standard AV590 engine. Variant AV590/1AG onwards appears to be of the later type with reticular tin rather than lead bronze bearings.
A further batch of AV590 engines were manufactured after the main Routemaster production run, although neither the LT or manufacturers code for these is included on the chart.