University of Arizona ^^7 



gines with a view to their usefuhicss on Arizona farms. Tractors 

 have been bought quite freely in Arizona and every type on the 

 market has been represented among those in use. During the past 

 year, particularly, many new tractors have been brought into the 

 State, partly on account of the widespread change from alfalfa 

 farming to cotton, which requires much more plo\ving. 



Many of the tractors first used in Arizona did not prove suc- 

 cessful. Some were too heavy and too expensive for the purposes 

 to which they were put, some suffered from operators who could 

 neither care for nor repair them, and some were ill-suited to the 

 soil conditions. In many cases the usual number of mules or horses 

 were retained on the farm, and repair bills have been very heavy. 



The writer has tended to favor the round-wheel type of trac- 

 tor ; four wdieels ; slow speed engines ; number of cylinders propor- 

 tional to the power, one or two cylinders for small tractors ; long 

 stroke ; and a transverse main shaft. As a rule, the more closely 

 a tractor engine resembles automobile engines, the less useful it 

 will prove to be. High speed eng'ines cannot burn low grade dis- 

 tillates. The rating of many tractors is not very liberal, and usually 

 they should be loaded with one less plow than they are advertised 

 to pull. The rating by manufacturers is very variable; of two trac- 

 tors much used* in Arizona, one rated at 20 horsepow^er and one at 

 25, the 20-horsepower tractor has the more power. Wide tires with 

 cleats are required for farm work. The utmost protection is needed 

 against the dust and fine sand which usually flies during the plowing 

 seasons. Gears should be housed and run in oil wherever possible. 

 Forced feed lubrication for cylinders and bearings is very desirable. 

 The standard speed adopted by tractor engineers is two and one- 

 third miles per hour ; higher speeds are not to be recommended. 

 The creeping tread tractor is justifiable on California unirrigated 

 grain lands where the spring planting is done while the ground is 

 still soft from the winter rains, and on difficult tasks such as drag- 

 ging the giant V's that clean the Yuma lateral canals. 



The criteria for estimating the relative success of a tractor on 

 any farm are : The type of farming, and number of days per year 

 when the tractor is used ; the mechanical ability of the OAvner or 

 operator ; and the fitness of the type and size of tractor to the soil 

 and nature of the work to be done. There are many farms where 

 tractors can be employed profitably ; there are many others where a 

 tractor would be a proverbial white elephant. 



The employment of tractors in custom work should be in- 

 creased. This implies that each tractor is operated by an expert 



