Should the LMS have built more Moguls and fewer Class 5s

40659 on Watford (1C) shed in 1960.

 

The Southern Moguls also had Cartazzi slide side contol, probably derived from the GWR arrangement, and their riding was not too good at speed. I suspect that there is little initial resistance to side movement with these slides. I recall that Stanier increased the initial side control load on his bogies on the LMS pacifics after his involvement with the investigation into derailements of Indian pacifics. This is a relatively simple modification to the Stanier spring side controlled bogie but difficult to achieve with slides or swing links. I understand that the P2 is to have a modified front pony truck based on the later V2 pattern - can anybody comment on the differences between the types

 

The Southern arrangement appears to have been adequate on the general purpose Moguls, while being shown to be inadequate on the heavier River tanks, which were dedicated express engines, and on the W freight tanks when experiments were made with them on passenger workings. I think pre-grouping 4-4-0s were still preferred to the Moguls where any genuinely fast running was in the offing.

The V2 pony truck was originally a double swing link design, which performed fine on the pre-war permanent way of the LNER (on which the Rivers had also been well behaved at speed on test), but there were several derailments during and after the war years.
As a result, they were modified with a spring control pony truck, directly cribbed from the 8Fs which had been built in LNER works.