The Diesel Electric Rail Motor (DERM) is a type of railmotor operated by the Victorian Railways in Australia.

History Originally built as a petrol electric rail motor (PERM), they were the longest-lived rail motor on the Victorian Railways, with the first entering service in 1928 and the last being withdrawn in 1991.

The rail motor, also known as the railcar, was a standard product of the US Electro-Motive Corporation (a predecessor of Electro-Motive Diesel) and built between 1924 and 1932, albeit to a smaller loading gauge and wider track gauge. The first was imported in 1927, assembled at Newport Workshops, and placed in service in 1928, initially running services to Bacchus Marsh. The bodies of the remaining nine were constructed at Newport Workshops using imported equipment and electrical components, and placed in service between 1930 and 1931.

The rail motors were initially powered by a Winton Motor Carriage Company petrol engine. When those wore out in the early 1950s, they were replaced with twin GM Detroit Diesel Series 71 engines, with a power output of , de-rated to match the original generator.

A DERM, with a DERM Trailer car attached, ran a regular passenger service on the South Gippsland line in the 1960s and 1970s. By the 1970s, the longest scheduled journey run by a DERM was the Bendigo to Robinvale run, last operated on 3 June 1978.

In 1976, RM 56 was fitted with a new seating arrangement, including rotating seats, using components from the Z carriage fleet. Capacity was reduced to 34 passengers, because the new seating arrangement was two either side of the central aisle rather than the previous two and three. The first-class end of the vehicle was moved towards the centre, closer to the engine, but providing a smoother ride by averaging the suspension of both bogies rather than just one. The trial arrangement was used on the Yarrawonga line, but patronage did not increase sufficiently to justify the retention of that service.

Following the changes to 56RM, 55RM and 61RM were extensively modified in the late 1970s, with the engines relocated, the body extended, and a new seating arrangement provided.Bray, Vincent & Gregory, Preserved Rolling Stock of Victoria, 2013, , p.62 The most obvious external difference was the fitting of aluminium-framed windows on the driver's cabin, and porthole windows for the engine room. Those "Super DERMs" were a familiar sight on the adjoining Mornington and Stony Point lines prior to the early 1980s.

Revised carriage working plans from 2 August 1987 required only two DERMs in service Monday to Thursday, with a third on Friday and Saturday and none on Sundays. As at 6 August the disposition was 56, 58, 63 and 64RM in service, though 64RM was "believed to be incapable of towing a trailer"; 55RM and 62RM were both being repaired at Bendigo Workshops, soon to be joined by 61RM, while 59RM and 60RM had both been withdrawn.

Class summary Motor units Railmotor Entered service Upgraded to DERM Withdrawn Current owner Current allocation Current status Notes 55RM "Super DERM" 1928-03-07 1952-10-27 1993 VicTrack Heritage Allocated to Yarra Valley Railway Under Restoration "Super DERM"; formerly at South Gippsland Railway 56RM 1930-03-29 1952-08-29 VicTrack Heritage Steamrail Victoria, Ballarat Pending restoration Upgraded interior pre Super DERM program 57RM 1930-04-16 1952-12-30 1982 Scrapped 58RM 1930-05-03 1952-05-10 VicTrack Heritage Allocated to Diesel Electric Rail Motor Preservation Association of Victoria Preserved; operational 59RM 1930-05-14 1953-05-23 Diesel Electric Rail Motor Preservation Association of Victoria Diesel Electric Rail Motor Preservation Association of Victoria Supply of spare parts Formerly with Mornington Railway, transferred September 2015 60RM 1930-06-18 1951-10-29 Diesel Electric Rail Motor Preservation Association of Victoria Diesel Electric Rail Motor Preservation Association of Victoria Pending restoration Stored at Newport Workshops 61RM "Super DERM" 1930-06-21 1953-10-29 1978 Victorian Goldfields Railway Victorian Goldfields Railway Preserved; operational "Super DERM" 62RM 1930-07-21 1952-01-26 Daylesford Spa Country Railway Daylesford Spa Country Railway Stored; Pending restoration 63RM 1930-08-07 1952-12-06 Daylesford Spa Country Railway Daylesford Spa Country Railway Preserved; operational 64RM 1931-04-27 1952-07-26 Diesel Electric Rail Motor Preservation Association of Victoria Diesel Electric Rail Motor Preservation Association of Victoria Under restoration

Trailers

Railmotor Entered service Withdrawn Scrapped Current status Notes 26MT 1930-04-29 1982-11-16 Preserved - Stored? Daylesford Spa Country Railway 27MT 1930-04-29 1982-11-19 28MT 1930-10-04 1981-06-09 1981-08-17 29MT 1930-09-26 1982-11-19 30MT 1930-09-26 1982-11-19

Preservation All but one of the DERMs have survived into preservation, with 57RM being the only DERM to have been scrapped. Four are operational, with the remaining five in various conditions, generally as a source of spare parts with long-term restoration in mind.

Of the regular DERMs, 58RM, operated by the Diesel Electric Rail Motor Preservation Association of Victoria, regularly runs tours on the Melbourne and Victorian broad gauge system, and 63RM runs trips on the Daylesford line with trailer 26MT when appropriate.

55RM is allocated to the Newport Railway Museum but was sub-allocated to the South Gippsland Railway. When the latter closed in 2016, it moved to the Yarra Valley Tourist Railway. 61RM operates on the Victorian Goldfields Railway between Maldon and Castlemaine.

28MT was sold privately, and as of 1998 was on private property in Dandenong.

See also Tourist and Heritage Railways Act Doodlebug (rail car) Weitzer railmotor

References

Further reading Our New Petrol Railmotor, Newsrail, May 1985