Trans Iranian Railway Beyer-Garratt Locomotives in Iran

Class Details by Steve Llanso of Sweat House Media

Class 86 (Locobase 691)

Data from Gavin Hamilton's excellent compilation of Garratt data posted at [] (6 September 2005); and A[rthur] E[dward] Durrant, Garratt Locomotives of the World (revised edition) (Newton Abbott, UK: David & Charles, 1981), p.62-63. See also "Railways in Iran - Part 10 - Motive Power" on Roger Farnsworth's website at []; and "Iran: the rarely visited East" on the FarRail Tours website at "[] last accessed 13 March 2023. Works numbers were 6787-6790 in 1936.

This Double Mountain quartet had the highest amount of EHS of all Garratts. Its grate also was substantial, but not the largest.They operated on the Iran State Railway's main line where it crossed the Elbruz mountains, Durrant reported, which required summiting at nearly 7,000 feet (2,134 m). Northbound runs included a 40-mile stretch of 1 in 36 (2.8%) adverse grade (identified by FarRail Tours as "between Pol-e Sefid up to the summit near the station of Gadouk").

Over such terrain, trailing road on a good day came to 400 tons, "but with the usual icy conditions," Durrant qualified, "350 tons was the normal load.

They apparently were worked very hard and by 1945 were reported "out of commission as they required new fireboxes, longitudinal cracks having developed across their tube-plates".

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID691
RailroadTrans Iranian Railway
Number in Class4
Road Numbers418-421/86.01-86.04
Number Built4
BuilderBeyer, Peacock
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)33,069 / 15,000
Weight on Drivers (lbs / kg)263,983 / 119,741
Engine Weight (lbs / kg)450,911 / 204,530
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)450,911 / 204,530
Tender Water Capacity (gals / ML)6756 / 25.59
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)55 / 27.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)53.10 / 1349
Boiler Pressure (psi / kPa)200.20 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)19.29" x 25.98" / 490x660 (4)
Tractive Effort (lbs / kg)61,962 / 28105.52
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.26
Heating Ability
Tubes (number - dia) (in / mm)
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)277.61 / 25.80
Grate Area (sq ft / m2)68.33 / 6.35
Evaporative Heating Surface (sq ft / m2)3612 / 335.69
Superheating Surface (sq ft / m2)874 / 81.23
Combined Heating Surface (sq ft / m2)4486 / 416.92
Evaporative Heating Surface/Cylinder Volume205.51
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation13,680
Same as above plus superheater percentage16,279
Same as above but substitute firebox area for grate area66,137
Power L112,970
Power MT866.54

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Wes Barris