The “Lancaster”, 1834
From John White
The Lancaster was Baldwin’s third locomotive – built in 1834. The boiler was a simple Bury type with a D-shaped firebox. The copper safety-valve column over the dome could be unbolted, thus opening a manhole for throttle and crown-bar maintenance. The throttle, located at the base of the dome, was a simple slide valve with three small rectangular openings. No records exist stating the number and size of tubes employed by the Lancaster, but a second-class Baldwin 4-2-0 of 1838 was noted as having 118 copper tubes 1-1/2 inches in diameter. The smokebox is round, an interesting departure from the common idea that round smokeboxes did not come into being until the introduction of the cylinder saddle.
The frame was wooden and was mounted outside of the wheels. No inside "safety" frames were used as on the English crank-axle engines. The frame was not clad with iron as was the practice for later Baldwin engines.
Baldwin's celebrated half-crank axle was used on the Lancaster. One half of the crank axle is omitted and its place is taken by the driving wheel. The Journal of the Franklin Institute, May, 1835, noted the advantages as follows: "The power of the engine is applied directly to the wheel, without the intervention of an arm of the crank thus diminishing the strain upon the axle, and consequently, lessening its liability to be broken. By this means, also, Mr. Baldwin has, in some measure, obviated the tendency of the driving wheels to twist upon the axles, and become loose; a very general and troublesome defect of locomotives." Other advantages were the possibility of wider boilers and the placement of the driving wheels behind the firebox since the connecting rod could pass between the boiler and frame. As good as this arrangement might appear to be, it defeated the two major advantages of inside connection - steady running and insulated cylinders. The cranks were at a great distance from the engine's center line and the cylinders were outside of the smokebox.
The truck was wood-framed with outside bearings. The forward weight of the engine was transferred to the truck by the bearing pin of the leaf spring attached to the main frame. The truck center pin was merely a pintle and did not carry any weight. It was placed a few inches behind the center of the truck in order to shorten the rigid wheel base.
The wheels were of cast iron in a T spoke pattern, with the ribs facing inside. The driving wheels had wrought-iron tires.
The valve gear is based on the motion devised by J. and C. Carmichael of Dundee, Scotland, in 1818. Joseph Harrison stated that a similar mechanism was used on early Delaware River ferries, and this may be where Baldwin got the idea for his locomotive valve gear. It is about the simplest motion that provides forward and reverse movement. A single fixed eccentric on the driving-wheel axle drives a girder-frame eccentric rod. The rod has two gabs, one facing the other. The rocker has two corresponding pins, one of which the upper or lower gab engages for forward or reverse motion.
The crosshead and guide are set back a considerable distance from the cylinder. This allowed convenient attachment to the frame and boiler and also helped to shorten the connecting rod. It should be noted that, since the driving wheels are behind the firebox, an unusually long connecting rod would be required if the crosshead guide were conventionally placed. The diamond-shaped crosshead guide also served as the feed-water pump body. The check-valve body at the end of the guide feed-water pump is held together by a stirrup. This permitted quick disassembly for cleaning out any obstructions clogging the check valves.
The crosshead and guide were massively made, not only to accommodate the pump, but also to withstand the racking strain imposed on the mechanism because it was not in line with the piston rod. This curious arrangement was used regularly by Baldwin through the 1840's. It was used as late as 1860 on the Active, a small four-wheel locomotive built for the Philadelphia and Reading Railroad.
Dimensions of the Lancaster
Cylinders 9" x 16"
Weight 7-1/2 tons
Steam pressure 120 lbs. per sq. in.
Rev. April 2010