| Western Australian Government Railways Z class | |
| Powertype: | Diesel-mechanical |
| Builder: | Robert Stephenson and Hawthorns, Newcastle upon Tyne as subcontractor to Drewry Car Co |
| Serialnumber: | Robert Stephenson and Hawthorns 7736-7738 |
| Builddate: | 1953 |
| Whytetype: | 0-6-0DM |
| Totalproduction: | 3 |
| Aarwheels: | C |
| Uicclass: | C |
| Length: | 5.750NaN0 |
| Fueltype: | Diesel |
| Primemover: | Gardner 8LW |
| Rpmrange: | 600-1700 rpm |
| Enginetype: | Four-stroke Inline Eight-cylinder Water-cooled Diesel engine |
| Cylindercount: | 8 |
| Cylindersize: | 4.5x |
| Transmission: | Mechanical |
| Maxspeed: | 28km/h |
| Poweroutput: | 140hp |
| T/E Starting: | 38.212NaN2 |
| Locobrakes: | Air brake |
| Trainbrakes: | Vacuum brake |
| Operator: | Western Australian Government Railways (former) |
| Numinclass: | 3 |
| Fleetnumbers: | Z1151, Z1152 & Z1153 |
| Locale: | Western Australia |
| Firstrundate: | October 1953 |
| Withdrawndate: | January 1983 |
| Currentowner: | Steamtown Peterborough Railway Preservation Society, Hotham Valley Railway & Boulder Loopline Railway |
| Disposition: | All preserved |
The Western Australian Government Railways (WAGR) Z class was a class consisting of three lightweight six-wheeled diesel-mechanical locomotives which were active in Western Australia from November 1953 to January 1983 and which have since been preserved.
Ordered in 1951[1] by the WAGR as part of its post-war rehabilitation program, the Z class was ordered from the Drewry Car Company at a cost of £12,000 per locomotive,[2] with their construction being subcontracted to Robert Stephenson and Hawthorn Ltd (RSH) of Newcastle, England. After the locomotives were built they were shipped from Britain to Australia, with Z1151 arriving at Fremantle harbour on 26 September 1953.[3] [4] Z1151 was demonstrated at the Perth Royal Show in October 1953[5] and entered service with the WAGR on 14 October 1953. The remaining two Z class locomotives would arrive around five weeks later.[6] This was despite the fact that their delivery date had originally being set for September 1952.
After entering service with the WAGR they were assigned to works as shunters on the jetty's and wharfs at Busselton, Bunbury and other ports.[7] They were capable of working for 22 hours per day, operating in three shifts, and alongside this could operate for five days on a single fuel tank.
By January 1954 the Z class were considered to have proven their worth to the WAGR. All three Z class locomotives were withdrawn from service on 1 January 1983 and subsequently were sold into preservation.[8]
After being withdrawn from service by the WAGR on 1 January 1983 all three Z class locomotives were sold into preservation.
The first member of the class, Z1151, would be sold to the Steamtown Peterborough Railway Preservation Society while the third, Z1153, was sold to the Boulder Loopline Railway.
The second member of the class, Z1152, would be sold to the Hotham Valley Railway (HVR) and was used by them on work trains during the rehabilitation of the Dwellingup - Etmilyn section of track throughout 1985–86. In June 2003 a request was made to the HVR by Works Infrastructure (E.D.I) to allow the for the use of Z1152 to assist in the construction of the new Urban Rail Car Depot at Nowergup on the new extension of the Northern Suburbs Railway and was transferred by road to Nowergup which was not connected by rail at time of movement.
After the return of Z1152 to the HVR, the locomotive has seen use as the shunter at Pinjarra depot.
The Z class is a lightweight diesel locomotive, weighing in at, which utilizes an 0-6-0 wheel arrangement and which is powered by a Gardner 8LW four-stroke eight cylinder in-line water-cooled diesel engine rated at 140 horsepower. The Gardner 8LW uses 110mm × 150mm cylinders and has a displacement of 11.160NaN0 while producing its power in the 600-1700 RPM range.[9]
Furthermore, the class uses a mechanical transmission, with the power being transmitted to the six driving wheels via external coupling rods. The class' braking system uses air for the locomotive and vacuum for the train. The class' maximum speed is 28 km/h (17 mph) and is capable of producing a tractive effort of 38.21 kN when starting.
| Number | Serial – RSH | Serial – Drewry | Status | Location |
|---|---|---|---|---|
| Z1151 | 7736 | 2401 | Static Display | Steamtown, Peterborough, South Australia |
| Z1152 | 7737 | 2402 | Operational | Hotham Valley Railway, Pinjarra |
| Z1153 | 7738 | 2403 | Stored | Boulder Loopline Railway, Kalgoorlie |