The Bridgeport evening farmer., 1916-03-15
MACHINE DESIGN EXPERT DETAILS
 CRAFTS SCIENCE
William Crosby Marshall Tn terests Remington Fore
 mems Club.


 Testing automobiles was made the subject of an inte9esting illustrated lecture, delivered .1ast night by Will liam Crosby Marshall. formerly pro- lessor of machine design at Yale, be- fore the Foremen's club of the Rem ington Arms & Ammunition Go. MT. Marshall is now in charge of the testing laboratories at the Bridgepor works of the company.
 The lecturer spoke to an audience of engineers and skilled mechanics who drank in every word he had to say with the keen relish of an expert. He explained in detail and by means of a number of lantern slides, the methods of testing the driving power Of an automobile by both laboratory and road experiments. The former are not so much in vogue as one would expect by the makers of high grade cars, who find it more conven- lent and less expensive to make their tryouts on the roads adjacent to their factories than to determine scientific ally beforehand just what they can expect of their cars before they leave the shop.
 The old method would suffice, Mr. Marshall said, if there was nothing more to be desired than the mere
 
 and the running parts of the cars. The laboratory tests, however, went much farther and provided data of a value which is worthy of greater recogniI ; tion that the present day manufac- turers apparently are willing to give. Consequently, the scientific work has been left principally to universities and technical schools.
 The first tests made to determine the power required to move automo- piles was by towing one machine by another with spring balance be- tween them. The pull thus obtained, taken with the speed and weight of the automobile. give the figures neces- sary for computing the high power road testing shows the acce1erating power, hill climbing ability. and full consumption. It also suggests the ad- justments required to make the car perform satisfactorily, before it is placed in the owners, hands. The ap- paratus comprises merely a gasoline measuring tank. a speedoE1eter and sometimes, an acce1erator which is an instrument for measuring the acce1- eration or retardatiOn of a motor car. l The laboratory equipment consists of a form of stand which will allow the car motor to drive the rear wheels of the car and at the same time to allow their resistance to rotation to
 
 two arrangements; either the support of the driving wheels on drums, which are turned by the rotation of the wheels themselves, or by driving some form of dynamometer either by belts or chains from the rear axle. The drums and electric dynamameters are located in a pit below the floor and the control of a. stand of this kind is placed in a, convenient position for the operator to vary the resistance and make corresponding observations on drawbar pull, gasoline consumption, speed, etc.
 A simpler kind of apparatus com prisus two drums fastened to the same shaft and provided with some kind of dynamometer to control the resistance of the drums to turning They are mounted beneath the test ing floor and the power measur em ent is made by a prong brake pulley keyed to the drum shaft. The brake adjustment is operated from the test ing floor by hand wheel and the pull on the brake arm is measured by platform scales on the testing floor. As the lever arm of the dynanometer is equal to the radius of the drums, the load on the scales should equal the drawbar pull. As an arrangement of levers produces a load on the scale of 100 pounds for eacn 1z0.4 pounds pull on the brake arm, and the frictiona1 resistance of the drums is 35 pounds, the drawbar pull equals the load on scales multi piled by 1,234 plus 35 pounds. An electric tachoneter measures the speed of the drums. The drum dia- meters are such that the circumfer- ence equals 7.51 feet, and 3O1 revolu- tions equals one mile.
 These vehicle tests determine:
 1. Loss in transmission gear and wheels.
 2. Friction loss in motor with and with out compression,
 3. Effective motor powers gas con- sumption and cooling water consump- tion at various speeds. 2
 4. Power of motor at constant speed with varying fuel supply.
 5. Front wheel losses.
 6. Gasoline consumption per, mile.
 MT. Marshall received 8 hearty vote of thanks at the conclusion of his lecture.
 Before the lecture the club dined as guests of the company. During the courses, songs were sung by V. S. Wren and a trombone solo by L. S. Baldwin. H. A. Hannum acconpan- jed on the piano.