94 LAWRENCE HARGRAVE. 



sloping axle bringing the disc in gear with the friction 

 pulley; this cannot be clone till the gyro sleeps with the 

 load on board. The lower end of the lever is provided 

 with a roller H that bears against the side of the wheel 

 hub. The framing I is two parallel tubes secured to the 

 underside of the lower casing B, and will accommodate 

 four bike saddles. The wheel K is spokeless and has two 

 pressed discs and a 3 inch tire. The spark shifter L, is at 

 a distance from the centre corresponding with the explosion 

 end of the cylinder. The carburetter is attached at M. 



Figs. 1, 2, 3, show a car with its centre of gravity 

 practically plumbing the tread of the tire. In this type, 

 if the wheel is put too suddenly into gear, the casing and 

 attachment may start spinning without revolving the 

 wheel. The lubricant, if excessive, will collect in the cup 

 of the piston and end of the crank chamber and cause a 

 disturbance of the balance of parts. A small force pump 

 inside the crank chamber worked off or through the main 

 crank pin can be used to remove the excess if an endurance 

 test is on. When the engine is stopped the oil can drain 

 off through a cock in the end of the footstep. With practice 

 a good course can be steered when the car is nutating. 



The short stroke and large diameter of cylinder facilitate 

 making large ports, as the velocity of admission and 

 exhaust is a limiting factor in the speed of revolution. It 

 is hard to say how short the stroke can be made. I think 

 the ideal rotary oil motor that must come will be like a 

 tossed coin ; and similar to the steam engine shown in Figs. 

 3, 4, pages 62, 63, of this Journal for the year 1898. 



The division of the power is a matter of interest. If the 

 car is on a perfect track, little push is required, leaving a 

 large balance to speed up the gyro and carry a large weight. 

 If the car is on a steep and stony hillside, plenty of push is 

 wanted, and some of the live load must walk to leave 

 enough gyro to sleep the remainder. 



