New Zealand E class locomotive (1922)

The New Zealand E class battery-electric locomotive represented the third unique type of locomotive class to be given the E classification in New Zealand. The first was the E class of nine Double Fairlie steam locomotives of 1872-75; the second E class consisted of a Mallet compound made in 1906; and as both were no longer operated by the New Zealand Railways in 1923, the classification was free to be used for a third time when the small battery-electric locomotive was delivered. This is the only time a classification has been used three times in New Zealand, though re-use happened a number of other times, arguably most notably when the A class of 1906 took the designation originally used by the A class of 1873.

New Zealand E class (1922)
E class no 1, battery-electric locomotive, between 1921-1930. A P Godber Collection, Alexander Turnbull Library.[1]
Type and origin Power type Battery electric Builder English Electric Build date 1922 Total produced 1
Specifications Configuration: ​  • Whyte 0-4-4-4  • UIC Bo'Bo' Gauge 3 ft 6 in (1,067 mm) Total weight 54 long tons (60 short tons; 55 t)
Performance figures Maximum speed 10 mph (16 km/h) Power output 176 hp (131 kW) Tractive effort 6,200 lbf (28 kN)
Career Operators New Zealand Government Railways Numbers 1 Locale Otira, Midland line First run April 1923 Last run 1930 Disposition Scrapped.

Introduction

This particular E class was ordered for service on the newly electrified Otira Tunnel section of the Midland line and was constructed in 1922.^[2]

In April 1923, English Electric delivered an order of six locomotives: five EO class mainline locomotives that collected electricity from overhead wires, and E 1, a sixth small battery-electric locomotive for maintenance duties; used in the 1920s.

E 1 had a wheel arrangement of Bo-Bo-2 (including a 4-wheeled battery tender for one battery section) under the UIC classification system. The battery of 216 "Ironclad Exide" cells was of 1,670 ampere hour capacity at a five hour rate of discharge. Power at an average of 400 volts went to four 22 kW (33 kW one hour rating) self-ventilating traction motors on each axle. Four DK 30 self ventilating traction motors were each of 44 hp (33 kW), for a total tractive effort of 6,200 lbf (28 kN) and a maximum speed of 10 mph (16 km/h).^[3]

It had a tractive effort of 27.5 kN at one-hour rating, and could haul 40 long tons (45 short tons; 41 t) at 8.5 mph (13.7 km/h) on the gradient of 1 in 33 (3 %) that prevailed between Arthurs Pass and Otira.^[3]

Braking was by airbrakes on engine and tender, a tramway type magnetic brake between each wheel set, and a screw type handbrake.^[2]

Withdrawal

The locomotive was written off around 1930 due to the costs involved in maintaining its batteries. Instructions were issued for any equipment that could not be re-used elsewhere from the locomotive to be dumped locally. E 1's cab can still be found alongside the track just south of Otira. The runner wagon for E 1 was stripped of its batteries and found use at Addington Workshops as a general-purpose wagon around the complex.