TILLAGE MACHINERY 93 



durable. The shanks may be constructed of the same 

 material as the beam and are provided either with a 

 break-pin device or knuckle joint to prevent breakage 

 when an obstruction is struck. 



Flat springs may be used for the shanks, and when so 

 used the term spring tooth is applied. Gopher shovels 

 are arranged to take the place of a special surface culti- 

 vator. Such an arrangement is not generally satisfactory. 

 A device is sometimes added to keep the shovels facing 

 directly to the front. Such a gang is spoken of as having 

 a parallel beam. 



Seats are of two styles : the hammock and the straddle. 

 The hammock seat is supported by the frame at each 

 side and offers a good opportunity to guide the gangs 

 with the feet. The straddle seat is more rigid, hence is 

 well adapted to the treadle- or lever-guided cultivators. 



The pivotal tongue is a device enabling the operator to 

 vary the angle with which the tongue is attached to the 

 cultivator frame. It may be used as a steering device, 

 or to set the tongue at such an angle that the cultivator 

 will not follow directly behind the team. It is very use- 

 ful in side hill work where the cultivator tends to crowd 

 down the hill. It may also be used in turning in a 

 limited space. 



The expanding axle permits the width of track to be 

 varied, necessary on account of various widths of rows. 

 It is accomplished by a divided steel axle or by the use 

 of collars upon the axles. The divided axle permits of 

 the use of the inclosed wheel box. It is an advantage to 

 have the half axles reversible in that when the axle end 

 becomes worn the opposite end may be substituted. 



Spacing. Some provision should be made to widen or 

 narrow the spacing of the gangs or rigs. On single-row 

 cultivators this is accomplished by. slipping the couplings 



