SEPTEMBER 1, 1915 



727 



made tractor is the one thai I he hiiildcr li:is 

 at liaiul. It' it runs steadily, witlioul ovcr- 

 lioatini;'; it' it is handily adjusted an<l re- 

 paired, and easily controlled, so much the 

 better. Most of the faults of the engine 

 work their vengeance either upon the oper- 

 ator or the rest of the machinery, though 

 they may not actually disqualify it for 

 tractor jnirposes. Some of them may be 

 al)sorbed in the transmission, if the builder 

 is skillful, althougli jirobably the transmis- 

 sion will gain nothing because of the extra 

 duty. An automobile engine, for iii.'^tance. 

 making 1000 levolutions per minute at the 

 crank-shaft can be reduced to about the 

 normal speed of 2o in the drive-wheels 

 thi-ough the transmission gearing; but part 

 of the latter will have to turn pretty fast, 

 and will wear out that much quicker; also 

 an extra shaft (with its attendant loss 

 through friction) will probably be neces- 

 sary in order to bring the sjieed down to 

 the reouii-ed point. 



jKiwer is iinpaired because of the weigiu 

 remo\ed from the drivers. Three-fifths of 

 ihe weight is needed there, to hold the 

 grout ers (or cleats across tlie face of the 

 drivers) snugly in the ground. This bal- 

 ancing of the parts can usually be best 

 accomplished by placing the engine near 

 Ihe rear axle as in Fig. 1, the transmission 

 in front of it, and the water-tank still 

 further ahead, its contents in some measure 

 icgulated by the weight required on the 

 fiont wheels. It is also best not to set the 

 engine back directly over the axle, as e\ery 

 jar occasioned by rough and stony ground 

 is communicated to it without any possibil- 

 ity of the sills absorbing part of the sliock. 

 In fastening down a tractor engine, special 

 ••are is necessary. 



If the crank-shaft is not exactly pai^allel 

 with the rear axle, some wheel or shaft in 

 llie transmission train will have to be a 

 1 rifle out of line Avith something else in 

 or(br tn rnrrc t tb." fnnlt. If a part of the 



Fig. 1. — Arrangini: the ]);irts of a well-balanced tractDi- 

 1. Rear ;vxle. 2. Engine. 3. Countershaft bearing. 4. Dift'erential-sliaft boa 

 5. Water-tanls. 6. Tractor sill. 



It is better, if possible, to set ihe engine 

 with the crank-shaft parallel to the dii\e- 

 wlieel axle, then there will be no bevel 

 gearing interposed, and no end-thrust to 

 contend with. Bet the engine just in front 

 of the rear axle — the closer the better. It 

 is then within easy reach of he operatoi's 

 I flat form, and the tractor balances well. 

 About two-fifths of the weight of the«trac- 

 tor should come upon the front wheels in 

 order to hold them firmly enough to tlie 

 ground for guiding purposes. If much less 

 than two-fifths, the tractor may work all 

 right when running empty on the level, and 

 the front truck lift clear of the ground, or 

 nearly so, when traveling up hill or on a 

 heavy pull. Of course it would then be 

 impossible to control the tractor. But if 

 I lie engine is placed too far forward the 

 tractor will steer unnecessarily hard be- 

 cau.se of the heavy weight on the steering- 

 wheels, and at the same time the tractive 



drive is chain transmission a little lee\\a_ 

 is possible, though it is best to have eAt'i 

 chain-and-sprocket members all perfectly 

 aligned. If gear-wheels entirely are used, 

 (he alignment cannot be too carefully made. 

 After the engine is once set it must be 

 so securely bolted that it cannot by any 

 possibility shift its position in relation to 

 il'.e axle or any of the transmission bear- 

 ings. Ordinary care may not be enough, 

 fur the jar and vibration are far greater 

 than in the case of a stationary engine. 

 Just how the fastening is to be done de- 

 pends upon the bolt-holes and the engine- 

 bed, but it must be done thoroughly. If 

 ihere is any chance to pass sub-sills across 

 the top of the engine-sills, and then bolt 

 these to the side sills of the tractoi*. it 

 .>lu)nld l)y all mean.s be done. Half-inch 

 bolts aie usually about rigid for light tract- 

 or V. oik. and it is safest to use a washer at 

 .•ach end, and two nuts instead of one for 



