1/21/2024 0 Comments Steam locomotive![]() The Heisler locomotive A Heisler locomotive - note cylinder location There was also an earlier Class A Climax with a vertically mounted marine-type steam engine, working through a similar drive-line, via a two-speed gearbox. The Climax locomotive Class C Climax locomotiveĬlasses B and C Climax locomotives have two inclined cylinders driving a transverse crankshaft, geared to a longitudinal driveshaft placed centrally on the locomotive and driving the powered trucks via internal gearing. The Shay locomotive features an offset boiler with a multiple-cylinder engine affixed to it on the opposite side, driving a longitudinal shaft geared to the axles via bevel gears (see also Ephraim Shay, inventor). The Shay locomotive Class C Shay (three driven trucks) This allowed use of relatively small driving wheels without sacrificing speed. The early Grasshopper (1832), Crab (1837) and Mud Digger (1842) locomotives built for the Baltimore and Ohio Railroad used gear ratios on the order of 2:1 so that each turn of the crankshaft caused about two turns of the driving axles. Richard Trevithick's Coalbrookdale Locomotive used a large gear instead of side rods to link the crankshaft to the driving axles, with a net 1:1 gear ratio. These were not the first locomotives to use geared transmission. The overwhelming majority operated on the North American region, but with a number in use in various parts of South America and a fair number in Australia and New Zealand, including home-developed types. Of the types, the Shay locomotive was the most numerous and best known. ![]() The vast majority of geared locomotives in the world were built to one of three distinct designs, whether licensed and official, or clones built after the expiration of key patents. Most were and are still single speed, but some did employ a variable-ratio gearbox and multiple ratios. Such a locomotive is a geared locomotive. The solution is to separate the crank from the wheels, firstly allowing for a reasonable piston stroke and crank radius without requiring larger than desired driving wheels, and secondly allowing for reduction in rotational speed via gearing. Although the trade-off of speed versus torque can be adjusted in favour of torque and tractive effort by reducing the size of the driving wheels, there is a practical limit below which this cannot be done without making the piston stroke too short on a directly-driven locomotive. Steeply graded lines, especially when the track is cheaply built and not suited to high speeds, will also favour the usage of a locomotive with a high tractive effort. These industries range from mining and quarry operations to forestry and logging operations. Many industrial applications require a low speed locomotive with ample starting tractive effort. This cannot be too large, for the locomotive will be unable to generate enough steam to supply those large cylinders at speed it cannot be too small, or the available starting torque and thus tractive effort will be too small, and the locomotive will not be able to start a train. The radius of the crank affixed to the wheel is of course less than this its radius determines the length of the piston stroke. Given the lack of any variable-ratio transmission between the piston engine and the wheels, the designer is forced to compromise between desired torque and desired maximum speed the radius of the driving wheels determines this. The maximum rotational speed is fairly fixed for a given engine technology. A shaft (seen towards the right of the photo) transferred power to a bevel gear (partially visible under a cover), which transferred power to the wheel. The steam locomotive, as commonly employed, has its pistons directly attached to cranks on the driving wheels thus, there is no gearing, one revolution of the driving wheels is equivalent to one revolution of the crank and thus two power strokes per piston (steam locomotives are almost universally double-acting, unlike the more familiar internal combustion engine).Ī wheel on a Shay locomotive. Instead, they are classified by their model and the number of trucks they have. Unlike conventional steam locomotives, they are not classified by their wheel arrangement. The geared steam locomotives that have been built have been for conventional track, relying on the adhesion between wheels and rail. This gearing is part of the machinery within the locomotive and should not be confused with the pinion that propels a rack locomotive along the rack between the rails. Steam railway locomotive with a geared transmission The Shay is among the most popular geared steam locomotivesĪ geared steam locomotive is a type of steam locomotive which uses gearing, usually reduction gearing, in the drivetrain, as opposed to the common directly driven design.
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