Camden & Amboy 6-2-0 "Crampton" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class John Stevens (Locobase 4834)

Some data from "Old Locomotive for the Camden & Amboy Railroad", Railroad Gazette, Volume 11 (15 August 1979), p. 435. (Thanks to Chris Hohl for his 10 November 2017 email noting the variety of cylinder bore and stroke combinations as well as an estimate of the adhesion weight.)

Worked out by president Robert Stevens and CME Isaac Dripps, this Crampton-like express engine was of such bizarre appearance as to be instantly recognizable. As with the Cramptons, the goal was to use very tall drivers for great speed (96" for five of them, 84" for the others) but to keep the center of gravity low. The result was a narrow, low-slung boiler leading a large anthracite-burning firebox.mounted so low that the fireman stood just 18" (457 mm) above the road bed throwing coal into a fire hole at the height of his ankles. Grate area was much too small, particularly in view of the anthracite fuel being used.

The rest of the design was equally unconventional. Three leading axles rode in a bogie positioned behind the smokebox and under the dual-tapered dome. So located, the bogie took more of the load than the drivers. (Locobase's entry uses Chris Hohl's report of 16,000 lb for the weight on the drivers.)

The long, slender cylinders were located over the bogie on each side and drove the tall, plated drivers. One engine may have had stroke as long as 38"(965 mm), which would have required a still more delicate-looking tube. (Chris Hohl identified three combinations--13"x34"/330 x 864 mm), 13"x38"/330 x 965 mm, & 14"x38"/356 x 965 mm.) Finally, in addition to the tall dome, a grossly outsized inversely tapered stack reared out of the boiler in front. It was nearly equalled by the tall cab, which stood on the firebox.

Despite early demonstration of the design's inadequate adhesion, deliveries continued until 1853. A six-car train (of small cars) was the engine's limit, but if the track was dry, the assembly would move at an impressive rate.

But Sam Dougherty, former Master Mechanic of the railroad, offered an adverse judgement in his comments to the Railroad Gazette: "The chief trouble with the engines was that they would not make steam [the very small grate likely being the culprit - Locobase], and, what was very curious, it is said that there was more trouble in making steam when they ran 'light' or alone without a train than there was with a train." (Locobase suspects drafting issues-the boiler and smokebox's natural draft was insufficient to burn coal when idling.)

"They were also very slow in starting." (Understandable, given the 8-ft drivers and very long stroke.)

Soon, however, the design was changed to a 4-4-0 layout with 72" drivers. The last of this class was retired in 1865.

Sources (Kinert, 1962; Brian Reed, Loco Profile 11, 1971, Reder (1974) differ on the number actually procured and over how long a period. Reed's Norris Locomotives study says 7 -- 28-32, 37, 38 -- but gives the dates of entry as April 1849, 2 in 1850, and the last 5 in 1851-1852.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassJohn Stevens
Locobase ID4834
RailroadCamden & Amboy
Number in Class8
Road Numbers28
Number Built8
Valve GearV-hook
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)
Weight on Drivers (lbs / kg)16,000
Engine Weight (lbs / kg)46,000 / 20,865
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)27 / 13.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)96 / 2438
Boiler Pressure (psi / kPa)100 / 6.90
High Pressure Cylinders (dia x stroke) (in / mm)13" x 34" / 330x864
Tractive Effort (lbs / kg)5088 / 2307.88
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.14
Heating Ability
Tubes (number - dia) (in / mm)110 - 2" / 0
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)14
Firebox Area (sq ft / m2)
Grate Area (sq ft / m2)15.20 / 1.41
Evaporative Heating Surface (sq ft / m2)
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)
Evaporative Heating Surface/Cylinder Volume
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1520
Same as above plus superheater percentage1520
Same as above but substitute firebox area for grate area
Power L1
Power MT

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