South African Class 61-000

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South African Classes 1-DH & 61-000
Rhodesia Railways Class DH1
SAR Class 61-000 61-006 (D750) 2.JPG
No. D750, later no. 61-006, Kassel, Germany, c. 1958
Type and origin
Power type Diesel-hydraulic
Designer Henschel & Son
Builder Henschel & Son
Serial number 29745-29751
Model DH-1420
Build date 1958
Total produced 7
Specifications
AAR wheel arr B-B
UIC class B'B'
Gauge 3 ft 6 in (1,067 mm) Cape gauge
Wheel diameter 1,054 mm (41.5 in)
Wheelbase 11,608 mm (38 ft 1.0 in)
 • Bogie 2,184 mm (7 ft 2.0 in)
Pivot centres 9,423 mm (30 ft 11.0 in)
Length:
 • Over couplers 16,551 mm (54 ft 3.6 in)
 • Over beams 15,507 mm (50 ft 10.5 in)
Width 3,004 mm (9 ft 10.3 in)
Height 3,948 mm (12 ft 11.4 in)
Axle load 18,900 kg (41,700 lb)
Adhesive weight 75,600 kg (166,700 lb)
Loco weight 75,600 kg (166,700 lb)
Fuel type Diesel
Fuel capacity 2,730 litres (600 imp gal)
Lubricant cap 546 litres (120 imp gal)
Sandbox cap Eight 0.13 m3 (4.6 cu ft) boxes
Electric system(s) Type 4 WHHP 315 batteries
* 64 V, 32 Cells, 280 amp/hr
* 2 Delco & Bendix starters
Prime mover GM-EMD type 6/567C
RPM range 835 maximum
Engine type 2-stroke diesel
Generator 10 kW (13 hp) 80 V
800 to 2,400 rpm (Auxiliary)
Cylinders 2 x V6
Cylinder size 215.9 mm (8.5 in) bore
254 mm (10.0 in) stroke
Transmission Voith Type L306r, 3 torque converters, using Cardan shafts
MU working 3 maximum
Loco brake Westinghouse
Train brakes Air & vacuum
Couplers AAR knuckle
Performance figures
Maximum speed 88.5 km/h (55.0 mph)
Power output 2 x 491 kW (658 hp)
Tractive effort:
 • Starting 197.2 kN (44,300 lbf) @ 9.6 km/h (6.0 mph)
 • 1 hour 148 kN (33,000 lbf) @ 16 km/h (9.9 mph)
 • Continuous 99.1 kN (22,300 lbf) @ 24 km/h (15 mph)
Loco brakeforce 77% @ 393 kPa (57.0 psi)
Career
Operators South African Railways
Rhodesia Railways
National Railways of Zimbabwe
Zimbabwe Iron and Steel Company
Class SAR Class 1-DH, Class 61-000
RR & NRZ Class DH1
Number in class 7
Numbers SAR 61-001 to 61-007 (ex D745 to D751)
RR & NRZ 3101-3106
Delivered 1959
First run 1959
Withdrawn 1971
Disposition 6 sold to RR

The South African Railways Class 61-000 of 1959 was a diesel-hydraulic locomotive.

Between May and July 1959, the South African Railways placed seven Class 1-DH Henschel type DH-1420 diesel-hydraulic locomotives in service, to also gain experience with other forms of diesel motive power than diesel-electric. The locomotives were later reclassified to Class 61-000. In 1971, six of them were sold to Rhodesia Railways.[1]

Manufacturer[edit]

The Class 61-000 type DH-1420 diesel-hydraulic locomotive was designed and built for the South African Railways (SAR) by Henschel and Son in Kassel, Germany. Upon delivery, the locomotives were classified as Class 1-DH and numbered in the range from D745 to D751. When the SAR adopted a new classification and numbering system for electric- and diesel-powered locomotives c. 1960, they were reclassified as Class 61-000 and renumbered in the range from 61-001 to 61-007.[1][2]

The Class 1-DH was acquired a year after the SAR had acquired its first diesel-electric locomotives to be built in quantity, the Class 1-DE, which had entered service in 1958 and which was later reclassified to Class 31-000. At the time, the SAR was still making extensive use of steam traction and limited use of electric traction. Its first diesel traction acquisitions were therefore the diesel-electric Class 1-DE and diesel-hydraulic Class 1-DH, to gain experience with both forms of diesel motive power.[1]

Diesel-hydraulic transmission[edit]

The more commonly used diesel-electric locomotive makes use of a diesel engine prime mover to propel either a generator (DC) or an alternator (AC) to generate electric power, which is then used to propel axle-hung electric traction motors, one per powered axle, to drive the locomotive wheels. It therefore works on the same principle as a regular electric locomotive, the only difference being that it generates its own electric power instead of collecting it from an external supply such as overhead catenary or a third rail.[1][3]

Diesel-hydraulic locomotives, on the other hand, use hydrokinetic transmission, also known as hydrodynamic transmission, in the form of torque converters to transmit power from prime mover to wheels.[4]

Characteristics[edit]

The Class 61-000 was a centre-cab locomotive which was powered by two General Motors Electro-Motive Division (GM-EMD) type 6/567C V6 prime movers, each with a Voith type L306r triple-converter torque converter and each driving the wheels of one bogie. Power was transferred to the axles through drive shafts. Unlike diesel-electric locomotives, where each axle is driven by its own traction motor, individual wheel-slip was not possible on the Class 61-000, since each bogie's two axles were interconnected through the drive shafts.[2]

The cab had two control stands and, since it was possible to start the six prime movers in three consisted locomotives from one engine cab, each control stand had six engine start buttons and six engine stop buttons. The electrical system was very complicated and unreliable, which eventually led to the locomotives being completely rewired in 1963.[1]

Service[edit]

South African Railways[edit]

The Class 61-000s spent their entire SAR working lives stationed at the Germiston diesel depot. One of them, no. 61-006, was involved in a head-on collision at Kaserne on 8 October 1966, and was eventually scrapped at the Koedoespoort workshops in Pretoria in September 1968. Problems with cracked axles resulted in the rest of the fleet being staged for repairs in 1967.[1][5]

Rhodesia Railways[edit]

In 1971, the remaining six locomotives were sold to Rhodesia Railways (RR), later renamed the National Railways of Zimbabwe (NRZ), where they became the RR Class DH1 and were renumbered in the range from 3101 to 3106.[1][2]

ZISCO[edit]

They were eventually resold to the Zimbabwe Iron and Steel Company (ZISCO) steel works at KweKwe in Zimbabwe. Most, if not all, were scrapped by 2001.[5]

Works numbers[edit]

The Class 61-000 builder's works numbers and renumbering upon reclassification and sale, are listed in the table.[6][5]

Illustration[edit]

References[edit]

  1. ^ a b c d e f g Paxton, Leith; Bourne, David (1985). Locomotives of the South African Railways (1st ed.). Cape Town: Struik. pp. 143–144. ISBN 0869772112. 
  2. ^ a b c RR Class DH1 dimensional drawing
  3. ^ South African Railways Index and Diagrams Electric and Diesel Locomotives, 610mm and 1065mm Gauges, Ref LXD 14/1/100/20, 28 January 1975, as amended
  4. ^ Diesel-hydraulic locomotive
  5. ^ a b c Middleton, John N. (2002). Railways of Southern Africa Locomotive Guide - 2002 (as amended by Combined Amendment List 4, January 2009) (2nd, Dec 2002 ed.). Herts, England: Beyer-Garratt Publications. p. 78. 
  6. ^ Henschel-Lieferliste (Henschel & Son works list), compiled by Dietmar Stresow