Roy V Wright (Ed.) 1916 Locomotive Cyclopedia of American Practice, Fourth Edition (New York: Simmons-Boardman Publishing Company, 1916), p. 189. See also [] website October 2000 and David B Leitch, "Is this the last Alco Mallet in steam?", Trains (June 1981), pp. 33-35. Works number was 53970 in December 1912..
This logging locomotive's delivery to the Taupo Totaro was delayed by six years because the TT couldn't pay for it. Although probably actually built in 1907, says David Leitch, its builder's plate shows "December 1912".
The 7 served the lumber company to which it was delivered from 1914 to 1945. Leitch quoted A E Durrant as describing this little engine as "one of the most delightful small Mallets ever built." The boiler featured a squat, spark-arresting cabbage stack, a dustbin sand domes, and a steam dome. Thick steam pipes snaked out of the sides of the steam dome down to the HP cylinders that drove the rear engine set. Unlike many Mallets, the 7 didn't have an intercepting valley that would have let live steam into the LP cylinders, which, Leitch comments, "effectively halves her initial tractive effort. Also, her manual screw reverse reputedly bred engineers with left arms like gorillas."
Although sold for scrap in 1945, it simply languished in the ferroknacker's yard until 1958, when it was bought by a group of Auckland enthusiasts and displayed at Putaruru. Glenbrook Vintage Railway purchased the engine as their #4 and restored it to operating service in 1977.
The 4 worked for the GVR until 2000, when it was placed in storage.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | unknown |
| Locobase ID | 4040 |
| Railroad | Taupo Totara Timber |
| Country | New Zealand |
| Whyte | 2-4-4-2 |
| Number in Class | 1 |
| Road Numbers | 7/4 |
| Gauge | 3'6" |
| Number Built | 1 |
| Builder | Alco-Schenectady |
| Year | 1912 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 4 / 1.22 |
| Engine Wheelbase (ft / m) | 24.12 / 7.35 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.17 |
| Overall Wheelbase (engine & tender) (ft / m) | |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 55,200 / 25,038 |
| Engine Weight (lbs / kg) | 69,000 / 31,298 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 23 / 11.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 32 / 813 |
| Boiler Pressure (psi / kPa) | 184.20 / 1270 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 10" x 14" / 254x356 |
| Low Pressure Cylinders (dia x stroke) (in / mm) | 16" x 14" / 406x356 |
| Tractive Effort (lbs / kg) | 9852 / 4468.80 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 5.60 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | 65 / 6.04 |
| Grate Area (sq ft / m2) | 15 / 1.39 |
| Evaporative Heating Surface (sq ft / m2) | 693 / 64.38 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 693 / 64.38 |
| Evaporative Heating Surface/Cylinder Volume | 544.54 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 2763 |
| Same as above plus superheater percentage | 2763 |
| Same as above but substitute firebox area for grate area | 11,973 |
| Power L1 | 3070 |
| Power MT | 490.45 |