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The large expansion ratio requires a large cylinder volume. To gain the maximum potential work from the engine a high reciprocation rate is required, typically 80% faster than a double-acting counterflow type engine. This causes the opening times of the inlet valves to be very short, putting great strain on a delicate mechanical part.
Similar to U engines, H engines consist of two separate flat engines joined by gears or chains. H engines have been produced with between 4 and 24 cylinders. An opposed-piston engine is similar to a flat engine in that pairs of pistons are co-axial but rather than sharing a crankshaft, instead share a single combustion chamber per pair of ...
Uniflow steam engine, a steam engine with a long uniflow cylinder that receives inlet steam at each end (for a double-acting engine) and exhausts through ports at the centre. Uniflow diesel engine, a two-stroke diesel engine with inlet through piston-ported fixed ports in the lower part of the cylinder, and exhaust through valves in the ...
In the 1980s, many U.S. production engine remanufacturers began reaming valve guides, rather than replacing them, as part of their remanufacturing process. They found that by reaming all the valve guides in a head to one standard size (typically 0.008 in. diametrically oversized), and installing remanufactured engine valves having stems that are also oversized, a typical engine head can be ...
The common valvetrain configurations for piston engines, in order from oldest to newest, are: Flathead engine: The camshaft and the valves are located in the engine block below the combustion chamber. Overhead valve engine: The camshaft remains in the block, however the valves are located in the cylinder head above the combustion chamber.
The usual locomotive valve gears such as Stephenson, Walschaerts, and Baker valve gear, can be used with either slide valves or piston valves. Where poppet valves are used, a different gear, such as Caprotti valve gear may be used, though standard gears as mentioned above were used as well, by Chapelon and others.
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In all models of this family of engines the cylinder heads are of aluminum alloy, screwed and shrunk onto steel barrels. Spark plug inserts and intake valve seats are made from aluminum-bronze alloy, while the exhaust valve seats are steel. The engines all employ hydraulic tappets which operate in aluminum guides that are machined into the ...