Search results
Results from the WOW.Com Content Network
Diagram showing lap and lead and their relation to valve travel. When on the move, a steam locomotive requires steam to enter the cylinder at precise times relative to the piston's position. [3] This entails controlling the admission and exhaust of steam to and from the cylinders with a valve linked to the motion of the piston. [3]
The connection between piston and main rod is a crosshead, which slides on a horizontal bar behind the cylinder. [2] [5] [3]: 55 Piston rod Connects the piston to the cross-head. [2] [3]: 61 Piston Produces the motion for the locomotive from expansion of the steam.
The cylinder is made pressure-tight with end covers and a piston; a valve distributes the steam to the ends of the cylinder. Cylinders were initially cast iron , but later made of steel . The cylinder casting includes other features such as (in the case of Stephenson's Rocket ) valve ports and mounting feet. [ 1 ]
The final 97 locomotives had piston valves mounted outboard of the cylinders, instead of inbound as previously built, giving the cylinder assemblies an outward cant at the top, rather than inward. All B6sa and B6sb locomotives were retrofitted with power reverse to make the frequent back-and-forth of switching quicker and easier.
An indicator diagram is a chart used to measure the thermal, or cylinder, performance of reciprocating steam and internal combustion engines and compressors. [1] An indicator chart records the pressure in the cylinder versus the volume swept by the piston, throughout the two or four strokes of the piston which constitute the engine, or ...
The Walschaerts valve gear is a type of valve gear used to regulate the flow of steam to the pistons in steam locomotives, invented by Belgian railway engineer Egide Walschaerts in 1844. [ 1 ] [ 2 ] The gear is sometimes named without the final "s", [ a ] since it was incorrectly patented under that name.
Schematic indicator diagram of pressure in a steam locomotive cylinder. The pressure in the cylinder declines after cutoff as the steam pushes the piston down its bore. Cutoff is one of the four valve events. Early cutoff is used to increase the efficiency of the engine by allowing the steam to expand for the rest of the power stroke, yielding ...
Indicator diagram showing steam pressure with piston movement. An expansion valve is a secondary valve within a steam engine. They represent an intermediate step between steam engines with non-expansive working and later valve gears that could provide for expansion by controlling the motion of a single valve.