South African type TM tender explained

South African type TM tender
Locomotive:NGR Class B of 1909
SAR Class 3B
SAR Class MC
Designer:Natal Government Railways
(D.A. Hendrie)
Builder:North British Locomotive Company
Date:1911-1912
Rebuilder:South African Railways
Rebuilddate:c. 1925
Rebuiltto:Type TL, Type XM1
Wheelarr:2-axle bogies
Length:24feet
Wheeldiameter:300NaN0
Wheelbase:16feet
Bogie:4feet
Axleload:10lt
Bogie 1:21lt
Bogie 2:21lt
Tenderempty:38960lb
Tenderworking:43lt
Fueltype:Coal
Fuelcap:8lt
Watercap:4000sigfig=3NaNsigfig=3
Stoking:Manual
Coupling:Drawbar & Johnston link-and-pin
Drawbar & AAR knuckle (1930s)
Operator:Natal Government Railways
South African Railways
Fleetnumbers:SAR 1451-1475, 1479-1488, 1607-1616

See main article: article and South African steam locomotive tenders.

The South African type TM tender was a steam locomotive tender from the pre-Union era in the Natal Colony.

The Type TM tender first entered service in 1911, as tenders to a second batch of 25 Mountain type steam locomotives which were ordered by the Natal Government Railways in that year. These locomotives were designated Class 3 on the South African Railways in 1912.[1] [2]

Manufacturer

Type TM tenders were built between 1910 and 1912 by the North British Locomotive Company (NBL).

The Natal Government Railways (NGR) placed its second batch of 25 Class B Mountain type locomotives in service in 1911. The locomotive and tender were designed by NGR Locomotive Superintendent D.A. Hendrie and built by NBL. Known as the Hendrie D, but officially designated Class B on the NGR, it was the first true Mountain type locomotive in the world.[1] [2]

The Type TM first entered service as tenders to these 25 locomotives. More entered service on the South African Railways (SAR) in 1912, as tenders to the ten Class 3B Mountain type and ten Class MC Denver type Mallet locomotives, both of which were also built by NBL.[1] [2]

Characteristics

The tender had a coal capacity of 8lt, a water capacity of 4000sigfig=3NaNsigfig=3 and a maximum axle load of 10lt.

Locomotives

During the classification and renumbering of locomotives onto the SAR roster in 1912, no separate classification and renumbering list was published for tenders, which should also have been renumbered according to the locomotive renumbering list. In most cases, an oval number plate, bearing the engine number and often also the tender type, was attached to the rear end of the tender. Three locomotive classes were delivered new with Type TM tenders, which were numbered or renumbered for their engines in the SAR number ranges as shown.[2] [3]

Classification letters

Since many tender types are interchangeable between different locomotive classes and types, a tender classification system was adopted by the SAR. The first letter of the tender type indicates the classes of engines to which it could be coupled. The "T_" tenders could be used with the locomotive classes as shown, although engine drawbars had to be replaced to suit the target locomotive in some cases. To couple Type TM tenders off the Class MC to the Classes 3 and 3B, the engine drawbar had to be 6feet long, and a drawbar had to be fitted to suit to couple any Type TM tender to Class 1A engines.[2]

The second letter indicates the tender's water capacity. The "_M" tenders had a capacity of 4000impgal.[2]

Modifications and rebuilding

Modification to Type XM1

At some stage before 1941, the intermediate draw and buffing gear of two of the tenders, numbers 1607 and 1615 off Class MC Mallet locomotives, were altered to an "X_" tender configuration. These tenders were reclassified to Type XM1.[2]

Rebuilding to Type TL

From c. 1925, several of the Type TM tenders were completely rebuilt by the SAR by mounting a new upper structure on the existing underframe, with 100sigfig=3NaNsigfig=3 smaller water tanks and a 101NaN1 larger coal capacity. These rebuilt tenders had a more modern appearance, with flush sides all the way to the top of the coal bunker. They were designated Type TL.[1] [2] [4]

The program to rebuild several older tender types with new upper structures was begun by Colonel F.R. Collins DSO, who approved several of the detailed drawings for the work during his term in office as Chief Mechanical Engineer of the SAR from 1922 to 1929. It was continued by his successor, A.G. Watson.[4]

Notes and References

  1. South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 Aug 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 3'6" Gauge/Spoorwydte. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. p. 43.
  2. South African Railways & Harbours/Suid Afrikaanse Spoorweë en Hawens (15 Aug 1941). Locomotive Diagram Book/Lokomotiefdiagramboek, 2'0" & 3'6" Gauge/Spoorwydte, Steam Locomotives/Stoomlokomotiewe. SAR/SAS Mechanical Department/Werktuigkundige Dept. Drawing Office/Tekenkantoor, Pretoria. pp. 6a-7a, 44.
  3. Classification of S.A.R. Engines with Renumbering Lists, issued by the Chief Mechanical Engineer’s Office, Pretoria, January 1912 (Reprinted in April 1987 by SATS Museum, R.3125-6/9/11-1000)
  4. SAR Mechanical Department. New Tender Tank - Classes 1, 1A, 2, 2C, 3, 3B. SAR Mechanical Department Drawing Office, Drawing L-6512/1, c. 1926.