Beira & Mashonaland/Rhodesia Railways Beyer-Garratt Locomotives in Rhodesia

Class Details by Steve Llanso of Sweat House Media

Class 13th (Locobase 716)

Data from A E Durrant, The Smoke That Thunders (Harare, Zimbabwe: African Publishing Group, 1997), pp. 96-100. See also Lionel Wiener, Articulated Locomotives (1930). Works numbers were 6269-6272 in March 1926, 6273-6280 in May.

According to Wiener, these Prairie Garratt locomotives, and the 14th Class that followed (Locobase 717), worked over a ruling gradient of 2%. In 144 miles, the railroad rose on an average of 1/2% grade from Villa Machado's 180 ft (54.9 m) above sea level to Umtali's 3,572 ft (1,089 m).

Durrant reports that the B&M's chief mechanical engineer was responsible for "permanently cur[ing] their anti-articulation phobia!". Gray asked for comments on the South African Railway's Garratts, saying that he understood: "The designers and makers of these engines claim for them great advantages of steadiness in running flexibility, round curves, ample steaming and simplicity in design conpared to other articulated engines."

Although the locomotives proved to be a good advertisement for Garratts, they were not without their faults. The plate frame (rather than the bar frames the railway typically preferred) proved "a mistake", wrote Durrant,especially in the use of Cartazzi axle boxes, but the biggest shortcoming was the valve design. He describes the Z-shaped port design as "tortuous" and piston valves with their heads too close together, the latter "giving a very small steam chest volume. Maximum valve travel was quoted rather pedantically as '3 3/4 + 1/64'" [95 mm].

Durrant notes that the 170-171 were fitted, probably between January and April 1929, with poppet valves actuated by Lentz oscillating cam valves. He couldn't determine if they had been removed, but the evidence suggested to him that they were.

The 13th class's early operational career served, "with typical incongruity" says Durrant, the steep grades from Umtali to Bila Machado in Mozambique. They later operated on branch lines and in heavy shunting (switching) work out of Salisbury in Rhodesia.

Drops in traffic caused the railway place the class in reserve through most of 1934-1935. All of the class returned to service in 1936 and with two exceptions, remained on the railway until scrapped in 1957-1958.

The two exceptions, 162-163, were sold to the Rhokana Corporation as their #4-5 in October 1939. The 5 was destroyed in a collision with a truck loaded with explosives.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID716
RailroadBeira & Mashonaland/Rhodesia Railways
Number in Class12
Road Numbers160-171
Number Built12
BuilderBeyer, Peacock
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m) 8.75 / 2.67
Engine Wheelbase (ft / m)19.25 / 5.87
Ratio of driving wheelbase to overall engine wheelbase 0.45
Overall Wheelbase (engine & tender) (ft / m)61 / 18.59
Axle Loading (Maximum Weight per Axle) (lbs / kg)29,120 / 13,209
Weight on Drivers (lbs / kg)173,712 / 78,795
Engine Weight (lbs / kg)273,840 / 124,212
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)273,840 / 124,212
Tender Water Capacity (gals / ML)5220 / 19.77
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 7.80 / 7
Minimum weight of rail (calculated) (lb/yd / kg/m)48 / 24
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)48 / 1219
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)16" x 24" / 406x610 (4)
Tractive Effort (lbs / kg)39,168 / 17766.33
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.44
Heating Ability
Tubes (number - dia) (in / mm)184 - 2" / 51
Flues (number - dia) (in / mm)32 - 5.25" / 133
Flue/Tube length (ft / m)12 / 3.66
Firebox Area (sq ft / m2)164 / 15.24
Grate Area (sq ft / m2)38.80 / 3.60
Evaporative Heating Surface (sq ft / m2)1840 / 170.94
Superheating Surface (sq ft / m2)380 / 35.30
Combined Heating Surface (sq ft / m2)2220 / 206.24
Evaporative Heating Surface/Cylinder Volume164.73
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation6984
Same as above plus superheater percentage8171
Same as above but substitute firebox area for grate area34,538
Power L17838
Power MT596.84

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