Y Class. No: 6

Y Class No. 6

Y Class No: 6 Diesel Locomotive | Don River Railway

Y Class Locomotive

Power Type: Diesel-electric
Builder: Tasmanian Government Railways Inveresk
Build Date: 1961-71
Total produced: 8
UIC classification Bo-Bo
Gauge 1,067 mm (3 ft 6 in)
Wheel diameter 3 ft 0 1⁄2 in (0.927 m)
Wheelbase 23 ft 10 in (7.264 m)
Length 44 ft 9 in (13.640 m)
Height 12 ft 2 1⁄2 in (3.721 m)
Axle load 14.5 tons
Locomotive weight 58 tons
Fuel type Diesel - English Electric 6SRKT Mk II (Y1-Y6)
Prime mover English Electric 6SRKT Mk III (Y7-Y8)
Cylinders Inline 6
Cylinder size 10 in × 12 in (254 mm × 305 mm)
Performance figures  
Maximum speed 45 miles per hour (72 km/h)
Power output 800 hp (600 kW)
Tractive effort 34,000 lbf (151.2 kN)
Train brakes Vacuum (Y1 & Y5 later converted to air)
Operator(s) Tasmanian Government Railways
Number in class 8
Number(s) Y1-Y8
First run 1961


The Y class were designed by English Electric and constructed by the Tasmanian Government Railways' Inveresk Workshops. Eight were built as mainline freight and passenger locomotives between 1961 and 1971.[1]

Following the success of the X class, the Tasmanian Government Railways decided to order additional diesel locomotives.

English Electric submitted plans that were quite similar to the South Australian Railways 800 class and Midland Railways of Western Australia F class.

They were slightly larger and more powerful than the X class.[1] They had a similar layout to the X class, a long hood unit with the cab at one end.

Construction began at the TGR's Inveresk Workshops in 1961, and three of the planned eight were completed relatively quickly. However, construction of the other five was slow, with the last not being delivered until 1971, by which time the design had become dated.

Technical details

The Y class were fitted with an English Electric 6SRKT Mark II (Mark III on last two) in-line six turbocharged diesel engine. They have a Bo-Bo wheel arrangement and end-platforms, making them visually different from the X class.[1]

In line with standard TGR practice of the time, they were fitted with hook-and-link couplers and vacuum train brakes (air on locomotive). With a light tractive weight of only 58 tonnes, a reasonably powerful engine of 825 horsepower (615 kW) and a fairly basic bogie design, gaining traction on long uphill grades was found to be difficult. They were noted to have a tendency to wheel-slip badly. Nevertheless, they were considered successful.

Later years

In March 1978 the Y class were included in the transfer of the Tasmanian Government Railways to Australian National. With the new transfer of twenty 830 class locomotives from South Australia and later purchase of ZB class and ZC class locomotives from Queensland Rail, the Y class were made redundant.

In the late 1970s and early 1980s all members of the Y class were retrofitted with stronger automatic couplers, which had by then become standard equipment. Two also received air train brakes in 1985,[2] with the others withdrawn following the cessation of vacuum braked services in 1988. Some of these have been preserved.[3]