1921.] Kepair & Maintenance of Threshing Machines. 975 



reversible, which exposes the opposite side of the concave 

 bars to wear, but a time will come when the concave wires 

 will have so worn that it is desirable to renew the concave. 



Straw Shakers and Riddle Cranks .—The bearings of the straw 

 shakers should be adjusted, and attention given to the small 

 cross bars, which are likely to get broken off, thereby increasing 

 the amount of cavings passing tlu'ough. In old machines 

 shaker blocks are generally of wood, and wear ond tear must 

 be talcen up and adjusted. 



■ Riddles and Sieves. — These should have attention. Care 

 should be taken to see that there are no holes worn in them, 

 and no places where the corn leaks out on the ground. Damage 

 is frequently caused by impatient attendants endeavouring to 

 clear a choked riddle, when in motion, by a thatch pin or any 

 other similar article near to hand. 



Screen. — The adjustable screen is likely to get out of order 

 through being closed with corn or other matter between the 

 wires; the wires get bent, leaving open spaces and in some 

 cases they become unsoldered from the expanding frame. I*f 

 the screen is in bad condition it is impossible to get an even 

 sample of corn without an undue proportion of good corn going 

 into the tailings. It is preferable to send it back to the makers 

 to be repaired. 



Straps and Belts. — All straps and belts should be maintained 

 in good condition and with as few buckles and lacings as 

 possible. It is also desirable to see that the shaker and riddle 

 belts are kept fairly tight, otherwise there may be an 

 unobserved loss of efficiency through slipping. 



Self-Feeders. — Efficient feeders are often difficult to secure, 

 and when this difficulty is experienced, contractors are advised 

 to try self-feeding apparatus, which in some districts is coming 

 into use. 



Engine. — Owing to the high price of fuel, it is desirable that 

 the steam engine should be maintained so as to *ive as 

 economical results as possible. If the piston or slide valve is 

 passing steam it should have attention immediately. 



Mechanical forced feed oil pumps for lubricating the sMde 

 valve and piston are most essential. 



The exhaust pipe, when using mineral cylinder oil, is likely 

 to fur up and become contracted. This throttles the exhaust, 

 reduces the power of the engine, and increases steam con- 

 sumption. It should therefore be kept thoroughly clean. 



In districts where bad water prevails, it is desirable tiiat 

 the boiler tubes should be withdrawn at frequent intervds, 



F 2 



