II III KQt'ATH'NS KH THK IMMVIluN KA TOR 5? 



volte, the two together making up the tension of the 



The gear wheel and the shaft // may be fixed in 

 pace, and the motor and its shaft .1 free to turn about /' 

 as a centre. This arrangement i> found in swing bridges, 

 turrets, and crane stages, where the gear wheel is placed 

 in a horizontal plane, the turret or stage rotating about 1 1 

 at a centre, and the -haft .1 attached to the rotating stage 

 so that when the motor turns the stage also turns. 

 lunation Ib is applicable here; the term n previously 

 used for the speed of rotation of the driving wheel now 

 baooBMi die ipeed : n tttionof i rond /'. hfle ' i- 

 still the resistance to motion, measured in inrh-{>ounds of 

 torque at the cent re of /'. In this arrangement / generally 

 consist* entirely of friction. The time occupied in getting 

 up speed is so large a part of the who].- time of working in 

 oases of this kincl that we must defer further consideration 

 of the problem until we have considered the question of 

 acceleration. 



K< (tint ion _'<> m n\ U- written in the form : 



.!/ - ./ , //. / / \' 



'VV~n , 



Kmm which we nee that when tin- .sjMttl und tl. 



i/ 

 fflbrt are fixed the rati fi.\e<l. Hy making largi- 



we can make M small ; in other \\onl-. if we are at liU-rty 

 to atljust the valiu*s of r and '/. we can reduce the weight 

 f the motor. To get M as small uMpcwMl.Ie we must have 



as large as possible, or r larg.- and - ; -mall, in IM..-I .:-.- 



