Локомотивтік күшейткіш: Бу машинасының қосымша күші

the term in rocketry

A locomotive booster for steam locomotives is a small supplementary two cylinder steam engine back gear connected to the trailing truck axle on the locomotive or one of the trucks on the tender. It was invented in 1918 by Howard L. Ingersoll, assistant to the president of the New York Central Railroad. A rocking idler gear permits the booster engine to be put into operation by the driver (engineer). A geared booster engine drives one axle only and can be non reversible, with one idler gear, or reversible, with two idler gears. There were variations built by the Franklin company which utilized side rods to transmit tractive force to all axles of the booster truck. These rod boosters were predominately used on the leading truck of the tender, though there is an example of a Lehigh Valley 4 8 4 using it as a trailing tender truck. A booster engine is used to start a heavy train or maintain low speed under demanding conditions. Rated at about at speeds from , it can be cut in while moving at speeds under and is semi automatically cut out via the engineer notching back the reverse gear or manually through knocking down the control latch up to a speed between , depending on the model and gearing of the booster. A tractive effort rating of was common, although ratings of up to around were possible. Tender boosters are equipped with side rods connecting axles on the lead truck. Such small side rods restrict speed and are therefore confined mostly to switching locomotives, often used in transfer services between yards. Tender boosters were far less common than engine boosters; the inherent weight of the tenders would decrease as coal and water were consumed during operation, effectively lowering the adhesion of the booster powered truck.

The booster was intended to make up for fundamental flaws in the design of the standard steam locomotive. To start off, most steam locomotives do not provide power to all wheels. The amount of force that can be applied to the rail depends on the weight on the driven wheels and the factor of adhesion of the wheels against the track. Unpowered wheels are generally needed to provide stability at speed, but at low speed they are not required, so they effectively 'waste' weight which could be used for traction. Therefore, the application of a booster engine to the previously unpowered axle meant that overall starting tractive effort was increased with zero penalty to the adhesion levels of the main engine. Additionally, the "gearing" of a steam locomotive is fixed, because the pistons are linked directly to the wheels via rods and cranks. Therefore, a compromise must be struck between ability to exert high tractive effort at low speed and the ability to run fast without inducing excessive piston speeds (which would cause failure), or the exhaustion of steam. That compromise means that, at low speeds, a steam locomotive is not able to use all the power the boiler is capable of producing; it simply cannot use steam that quickly, so there is a substantial difference between the amount of steam the boiler can produce and the amount that can be used. The booster engine enabled that wasted potential to be put to use. The increased starting tractive effort provided by the booster meant that, in some instances, railroads were able to reduce the number of, or eliminate the use of additional helper locomotives on heavier trains. This resulted in lower operating and maintenance costs, higher locomotive availability and productivity (ton miles), and ultimately, greater profitability.

Boosters were costly to maintain, with their flexible steam and exhaust pipes, idler gear, etc. Improper operation could also result in undesirable drops in boiler pressure and/or damage to the booster. The booster and its associated components also added several tons of weight to the locomotive which would be considered "dead weight" at speeds above which the booster could not be used. Additionally, if the booster suffered a failure where the idler gear could not be disengaged, the entire locomotive would be speed restricted to 20 mph or less, until it could be taken out of service to facilitate repairs, decreasing locomotive availability.