STEAM- WINDING DRUMS FOR PLOUGHING, ETC. 



components of the total traction, if the soil is dry this 

 automatic anchor cannot slip, as it is kept in the soil by the 

 discs cutting into it ; and, if its weight is not sufficient, it may 

 be increased by means of boxes filled with earth. If the port- 

 able engine and winding drum carriage are carried on iron 

 rails, allowing easy displacement by block and tackle, the 

 fixed pulley in front may be dispensed with, and the cable 

 passed over the pulley in front of the automatic anchor, but 

 in this case the pulley must be secured by two or three 

 anchors, for, the angle of the cable being more acute, the 

 strain on the pulley is greater. 



The system being established as above, or in a similar 

 manner, it remains to study the conditions which the different 

 parts are to fulfil to obtain the best work. We will first study 

 the winding drums. In double-effect systems one cable winds 

 over one drum hauling the plough, while the other cable un- 

 winds. This unwinding is irregular, especially if the soil is 

 dry and stony. The plough proceeds by jerks ; the return cable 

 unwinds spasmodically, and may get entangled between the 

 flanges of the drums or the gearing mechanism. To avoid 

 this trouble the drums must be provided with brakes, 

 acting slightly but steadily during the unwinding. One of 

 the simplest systems of brakes is that shown in Fig. 79. It is 

 made of a circular band of flat iron e terminated at both ends 

 by two pieces at right angles, carrying at their extremities 

 two threaded holes in which a thumb-screw Y works. The 

 flat iron bar carries inside wooden shoes b, and outside cleats 

 t, rounded on one side and flat on the other. The shoes b rest 

 on a circle provided with a flange fixed on the drum T or cast 

 with it, upon which the pressure of the brake acts. When 

 the drum T revolves in the direction of the arrow (position 1), 

 that is to say, unwinds the cable, one of the cleats t comes in 

 contact with the stop m, held in position by a cast-iron sup- 

 port bolted on the frame, and the brake acts. If, on the 

 contrary, the drum T revolves in the opposite direction 

 (towards the plough), one of the cleats t comes in contact 

 on its rounded part with the stop, which is lifted (position 

 2), and the brake does not act. The lever k allows the stop m 

 to be lifted by hand, and the brake to remain free. This is done 

 when a certain length of cable has to be unwound by hand. 



It is also necessary to make the hauling cable wind 

 regularly round the winding drum. Most of the winding 

 drums on the market are not provided with winding guides ; 



