Compressed air . has been im-proved. The efficiency o£ the motor hasincreased in everj- wa3\ also, in a sur-prising degree—the losses in the oldertypes being due to large leverages andconsequent working loose and wearing ofparts, and to poor piston fits. It shouldhere be stated, however, that in this seriesof tests the machines selected were all ingood condition, the new ones having been warmed up by a few weeks of active was driven at a point far away from thecrank, and as no provision was madefor balancing, the vibration was excess-ive. The oiling also was unsatisfactorA*.In the old w-ing-ty
Compressed air . has been im-proved. The efficiency o£ the motor hasincreased in everj- wa3\ also, in a sur-prising degree—the losses in the oldertypes being due to large leverages andconsequent working loose and wearing ofparts, and to poor piston fits. It shouldhere be stated, however, that in this seriesof tests the machines selected were all ingood condition, the new ones having been warmed up by a few weeks of active was driven at a point far away from thecrank, and as no provision was madefor balancing, the vibration was excess-ive. The oiling also was unsatisfactorA*.In the old w-ing-type motors it wasdifficult to keep the mechanism properlyoiled, as the air driving the motor carriedout the oil in the exhaust. In the latertypes, the cranks run in oil, and the aircomes in contact with the piston only. Simplicity of design, compactness, few-ness of parts, are the elements that char-acterize the later tj-pes of motor. Thestrongest motor is not the heaviest; themost powerful is not the AN UNDESIRABLE JOB, MADE EASY BY USE OF ANGLE DEVICES IN CONNECTION WITH ANAIR MOTOR. service and the older machines havingbeen previously put in thorough repairand adjustment, so that each machinemight give the best performance of whichit was capable. Referring to the last of the three dia-grams, the line representing relative costsof operation per unit of work is moststriking. The earlier casings and parts wereheavy and large, to withstand as yetundetermined strains. Little attentionwas paid to the selection or testing of thematerials used in the motor. Tlic tool In examining into the reasons for theincreased economy and compactness ofthe later types in proportion to powerdeveloped, it may be stated that a highernumber of revolutions of tool-socket perminute has been one of the factors. Inone of the later types a two-speed gearprovides for both slow and fast opera-tions and this has been found of greatuse. An important point is tliat in the ear-lier types, the repair
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectcompres, bookyear1896
