. Steam engines, a thorough and practical presentation of modern steam engine practice . ore easily handled. When the cranks of the cross-compound engine are at 90 degreeswith each other the low pressure piston is not ready to receive thesteam when the high pressure exhausts; therefore, there must be areceiver to hold the steam until admission occurs in the low. Suchengines are called cross-compound, because steam crosses over from 28 STEAM ENGINES one side to the other. Sometimes Instead of having the cranks at90 degrees, they are placed together or opposite. Then the strokesbegin and end tog
. Steam engines, a thorough and practical presentation of modern steam engine practice . ore easily handled. When the cranks of the cross-compound engine are at 90 degreeswith each other the low pressure piston is not ready to receive thesteam when the high pressure exhausts; therefore, there must be areceiver to hold the steam until admission occurs in the low. Suchengines are called cross-compound, because steam crosses over from 28 STEAM ENGINES one side to the other. Sometimes Instead of having the cranks at90 degrees, they are placed together or opposite. Then the strokesbegin and end together, and the high can exhaust directly into thelow without a receiver. A tandem-compound engine, Fig. 21, has both pistons on onerod, the high pressure piston rod forming the low pressure tail engines are less expensive because there is but one set of recip-rocating parts instead of two, but like simple engines they have thedisadvantage of dead points. Triple Expansion Engines. Triple expansion engines expandthe steam in three stages instead of two. There are usually three. Fig. 21. Section of Cylinder and Valves of a Tandem-Compound Engine cylinders, viz, the high, the intermediate, and the low, arrangedwith cranks 120 degrees apart. This gives a more uniform turningmoment than a compound. Sometimes there are four cylinders onthe triple expansion engine, viz, one high, one intermediate, andtwo low. This arrangement gives better balance and is often usedin marine work. For triple engines there must be a. receiver between each twocylinders. Fig. 22 shows the essential features of a triple expansionengine. Quadruple Engmes. Quadruple engines expand their steam infour stages instead of three. Multiple expansion engines are nearlyalways condensing. STEAM ENGINES 29 Cylinder Ratios. There are several considerations to be remem-bered when proportioning the cyUnders of the multiple expansionengines. The ratio of the cylinders should be such that each devel-ops nearly the sa
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectsteamen, bookyear1920
