262 APPLIED SCIENCE 



One mile per hour corresponds to 473 revolutions per minute of 

 the motor. 35'21 inch pounds at the motor spindle are re- 

 quired for a pull of 100 Ibs. at the rail. Figs. 10 and 11 show 

 a locomotive designed by Mr. A. C. Jameson, when I was per- 

 sonally unable to attend to work. This locomotive, which is 

 called the ' belt locomotive,' shows a great advance on its pre- 

 decessor. The general arrangements of the upper nest grip is 

 retained, but a most ingenious modification has been intro- 

 duced, by which the discs, C C, run on one path on the rollers, 

 A A, while the rod runs on another. In this way the dirt from 

 the line is never conveyed to the driving disc surface between 

 A and C. Moreover, these frictional surfaces, which are points in 

 the first form, have become lines in the second. This type answers 

 admirably. The weight is carried by a roller, B, between the 

 gripping discs, an arrangement contained in one of my first 

 small models, and wrongly rejected in the first large locomotive. 

 With this subdivision of weight, the gripping wheels are much 

 less likely to rise, and can be made very shallow. In the actual 

 locomotive, these gripping wheels are of an open inverted A shape, 

 which has certainly run very well, although I prefer at present 

 the upright V shape, which closes under the rail, as used in the 

 model before you. 1 Both of the gripping rollers drive, as in 

 the first type. The cross shaft is driven by a belt on a 20-inch 

 pulley, D ; the other end of the belt runs on a 2-inch pulley, 

 E, on the motor spindle. The friction due to the pull of this 

 belt on the motor spindle is relieved by friction rollers. This 

 locomotive runs extremely safely and steadily on the line ; in- 

 deed I am not aware that it has ever been thrown off. The fol- 

 lowing are particulars of its construction : Weight, with a 96 Ib. 

 1 horse-power motor, 269 Ibs. ; wheel-base, 2 ft. 6 in. ; diameters 

 of driving rollers, 6 in. ; 4*94 revolutions of motor per one re- 

 volution of driving wheel. A couple of 60'6 inch Ib. on the motor 

 is required for 100 Ibs. pull at the rail ; 276 revolutions of motor 

 correspond to one mile per hour on the rail. The only improve- 

 ments I have to suggest in this design are first, the addition 

 of gear which will give a higher speed of motor for the normal 



1 It has been suggested in an article in the Engineer that this grip is lees 

 powerful than the form first described. The suggestion can only be due to 

 some misunderstanding ; the gripping action is identical in the two cases. 



