When the VR built their AEC railmotors, it was realised that extra capacity was needed. To this end, they built the RailMotor Trailers, or MT class, specifically designed for the AEC railcars. When later railmotors were introduced, the same rollingstock code was used, resulting in the MT class being one which included several different designs. It was not uncommon for a train to be composed of one railmotor and two, three, or in rare cases, four trailers.
These were numbered 1 to 24, painted red to match the four-wheeled AEC railmotors, and were the only MT cars that were four-wheelers. They were built between 1922 and 1925, to a few slightly different designs.
25 MT was converted from locomotive-hauled wooden bogie passenger carriage 20 APL in 1928, for use with the first PERM.
Numbers 26 to 30 were built in April, September, and October 1930 (when more PERMS entered service) and were painted red initially, although a different shade of red to the AEC trailers. They were of steel bodied construction, and similar design to the PERMS. When the PERMs were converted to DERM (diesel) railmotors in the mid-1950s, these five trailers were also painted in blue and gold to match.
More details: DERM → Trailers
(3rd) 8, 11, 12, 14, and 16 ABC were converted from locomotive-hauled wooden bogie passenger carriages, between April and July 1930, specifically for use with the ten PERM railmotors. These were originally built in 1890 & 1891 as non-corridor, five-compartment first-class carriages with guard’s compartment (ADAD, later AC class), and had been extended between 1909 and 1912 by the addition of two more passenger compartments. They were intended to become Dogbox ‘M’ cars. When that conversion scheme was halted, they returned to the locomotive-hauled fleet (with varying degrees of conversion evident), and were later converted to second-class (BC) carriages shortly before becoming railmotor trailers. All were scrapped between 1939 and 1961.
Trailer cars 50 – 64 were Walkers railcar trailers placed in service between 1948 and 1954. They were primarily placed behind the 102 hp (76 kW) and 153 hp (114 kW) variations, but occasionally were coupled to 280 hp (210 kW) versions. Of note, is that Walker trailers 50 and 51 were originally classed RMT instead of MT. They were re-classed MT by 1949.
More details: Walker railmotor → Trailers