K 917 is Steam Incorporated’s rescued example of the NZR’s first class of 4-8-4 locomotive.
- Locomotive running number: K917
- Designed by: New Zealand Railways
- Built at: NZR Hutt Workshops, Wellington
- Date built: 1934
- Builders number: 294/34
- Date entered service: 1935
- Date withdrawn: 1964
- Current condition: Stored long term awaiting restoration
- Wheel arrangement: 4-8-4
- Driving wheel dia: 54”
- Cylinders: (2) 20” x 26”
- Valve gear: Walschaert
- Working pressure: 200 psi
- Weight in working order: 140.1 tons
- Overall length: 69’ 8”
- Tractive effort: 32,730 lb(@ 85% boiler pressure)
- Fuel: Oil (converted from coal in 1949)
- Capacities: Fuel, 1570 gallons. Water, 5000 gallons.
Conceived as a simple alternative to the unsuccessful G class Garratt articulated locomotives on the North Island Main Trunk, the K class was originally proposed to be a 4-8-2. However, the maximum axle load of 14 tons, meant a 4-8-4 design was adopted.
All 30 were constructed at Hutt Workshops between 1932 and 1936. The class used plate frames, partial mechanical lubrication, Franklin butterfly firehole doors. While the main driving axles and trailing bogie had plain bearings, unlike the later Ka and Kb classes, the leading bogie and tender bogies had roller bearings.
The class gave excellent service through the 1930s, predominantly on the NIMT. Their success led to construction of 35 Ka class for North Island service, beginning with Steam Incorporated’s Ka 945, and six Kb class for South Island service.
While generally reliable, trouble at first was encountered with the long-travel Walschaerts valve gear, and with the plate frames. While the valve gear problems were largely solved by reducing travel from the original 8 inches to 7 1⁄4 inches, the plate frames continued to crack especially around the firebox cradle.
During the 1950s a programme of fitting replacement frames similar to that used on the Ka and Kb classes began. However, only some were modified, including 917.
During coal shortages after the Second World War, the entire K and Ka classes were modified to burn fuel oil, 917 being converted at Otahuhu Workshops in 1949.
Initially, the first 14 K class were fitted with headlights mounted on the front of the smokebox, but following a styling decision, the headlights on later locomotives, including 917, were recessed into the smokebox, giving the distinctive K “look”. Earlier locomotives were soon modified to the new look,
Originally fitted with twin Westinghouse pumps mounted at the front of the boiler, in 1955 K 917 was among 10 of the class fitted with a cross-compound pump mounted through the running board on the fireman’s side.
During the rundown of the K class in the late 1950s and early 1960s following the introduction of the Da class diesel electric locomotives on the NIMT, most K class were concentrated on Wanganui to cope with traffic on the heavily graded Marton-New Plymouth line. However, 917 was one of a small number to work out its last years of active service based on Frankton depot, while a handful were at Palmerston North or Auckland.
While most of the class were scrapped after retirement, 917 was one of a trio – along with 911 and 921 – adapted to supply steam at Hutt Workshops. The locomotives survived in this form until 1988 when they were deemed surplus and put up for sale.
After purchase by Steam Incorporated, K 917 was stored at Gracefield, near the Hutt Workshops before being moved with the tender of K 928 to Paekakariki in 2001.
The locomotive is not complete, missing major items, and has only been considered a possible long-term restoration project.