488 BEPOKT— 1886. 



unable to drive the sphere, and the only other way for the load to fall 

 was by the wheel sliding over it. By arranging so that the machine 

 should always stop at this point, and nowhere else, the danger to the ball 

 was averted, a brake could be dispensed with, and starting and stopping 

 easily arranged. 



The manner in which the difficulty was overcome is clearly shown in 

 fig. 1. The rigid arm (a) connecting the two guide-wheel frames (g) 

 has a lug cast on ih "When the axis of the ball passes through the 

 point c, the lug throws back the end (/) of the bell-crank lever (d), and 

 thus, by means of a connecting rod and two other levers, throws up an 

 arm (h), with a tooth on its free end. This tooth engages in a thread of 

 coarse pitch on the sliding part of the clutch (p) . As the clutch revolves 

 the screw draws out the sliding part, thus stopping the machine. When 

 the machine is started the arm (a) is moved, the bell-crank lever returns 

 to its former position, the tooth (h) falls away from the thread, and the 

 spring (s) forces the clutch into gear, and the ball again revolves, but 

 with its axis now in a safe position. 



There is the objection to this arrangement that only at one point of 

 the revolution of the clutch can the arm be moved so as to reverse the 

 driven shaft, and this causes delay in working. 



In the hoist next made (figs. 3 and 4) a much better device is used, 

 whereby it is only possible to stop the machine at one point of the revola- 

 tion of the driving- shaft, and thus there is little fear of stopping when it 

 is desired to reverse the motion. If, however, the axes of the balls are 

 left so as to pass through (Z I), not more than one or two revolutions 

 can take place before they stop, and there is not sufficient time for any 

 harm to be done. 



Referring to figs. 3 and 4, the handle (h) attached to the vertical shaft 

 (A;) controls the change of axes of the balls. When at the right position 

 a nipple on the bell-crank lever (m) moves the lever (r), and lifts the 

 end (z). Meanwhile the revolution of the driving-shaft brings the arm 

 (s) against (s), (s) and the nut (d) thus cease to revolve, and the rod (g), 

 being advanced through the nut, throws the clutch out of gear. On turn- 

 ing the handle the arm is released, and the spring (s) moves the rod 

 axially, and brings the clutch into gear. This arrangement answers per- 

 fectly, allowing a free movement of the axes of the balls, with quick 

 reversal of motion and change of speed. 



Bearings. — Great attention has necessarily been bestowed on the 

 bearings, the following conditions being required : — 



(a) Diameter as small as possible, to reduce the loss in friction. 



(b) Such arrangements for lubrication as shall be as far as possible 

 perfect. 



(c) Security from escape of lubricant on to the rolling surfaces. 



The conditions of working are unusually severe, and the bearings, 

 which have been found to work satisfactorily, are therefore described in 

 detail, and illustrated in figs. 5, 6, 7, 8, 9, and 10. 



Fig. 5 shows a bearing suitable for taking an oblique thrust. The 

 part (/) is a portion of the framing of the machine. The bush (a) is of 

 phosphor bronze, both the ends of the shaft (b) and set screw (c) have 

 steel points, made as hard as possible, with a small hole drilled in the 

 centre of each. Stauffer lubricant is introduced through the tube (h) 

 into the inside space. 



