Popular Science Monthly 



must be turned first in one direction and 

 then "in the other. 



A valve grinding tool patterned largely 

 after a breast drill is shown at Fig. ii, 

 D. This is worked in such a manner 

 that a continuous rotation of the operat- 

 ing crank will result in an oscillating 

 movement of the chuck carrying the 

 screw driver blade. The bevel pinions 

 which are used to turn the chuck are 

 normally free unless clutched to the 

 chuck stem by the sliding sleeve which 



131 



ing the surface of a valve head when the 

 usual form of valve head truer is not 

 available is indicated at Fig. ii, £. The 

 valve heads are usually provided with 

 a small depression in the center known 

 as a countersink which is designed to 

 act as a support foe the valve when it 

 is being machined from the forging. The 

 stem of the valve is caught in the chuck 

 of a bit stock and rested on any sharp 

 point on a wall or bench. This can be 

 easily made by driving a large wire nail 



\/dlve Cages 



Tappets 



Twin Clylinder 

 Casting 



/ Cdmshdft 



Crdnkshdft 



Oil Troughs 



Fig. 10. A part sectional view of Buick Motor, showing method of valve mounting 

 in easily removable valve cages 



must turn with the chuck stem and 

 which carries clutching members at each 

 end to engage similar members on the 

 bevel pinions and lock these to the chuck 

 stem, one at a time. The bevel gear car- 

 ries a cam piece which moves the clutch 

 sleeve back and forth as it revolves. This 

 means that the pinion giving forward mo- 

 tion of the chuck is clutched to the 

 chuck spindle for a portion of a revolu- 

 tion of the gear and clutch sleeve is 

 moved back bv the cam and clutched to 

 the pinion giving a reverse motion of 

 the chuck during the remainder of the 

 main drive gear revolution. 



A method that can be used for smooth- 



in the bench from underneath so that 

 the point projects through the bench. 

 The bit stock is briskly turned by a help- 

 er and the rough spots are removed from 

 the seat with a fine file, care being taken 

 not to change the taper of the valve head. 

 The valve stem could be turned much 

 faster and a superior finish obtained if 

 a breast drill were used instead of a bit 

 stock, though with care a very credit- 

 able job may be done with the latter. 



One of the things to watch for in valve 

 grinding is clearly indicated at Fig. ii. 

 F. It sometimes happens that the ad- 

 justing screw on the valve lift plimger 

 or the valve lift plunger itself does not 



