194 STATE BOARD OF AGRICULTURE 



one-half inches. The following is a partial summary of their conclusions. (Missouri 

 Bulletin 139, page 165.) 



"I. On Macadam street, as an average of the two trials made, a load of 2,518 

 pounds could have been hauled on the broad tires with the same draft that a load 

 of 2,000 pounds required on the narrow tires. 



"II. Gravel road. In all conditions of the gravel road, except when wet and 

 sloppy on top, the draft of the broad tired wagon was very much less than that of 

 the narrow tired wagon. Averaging the six trials, a load of 2,482 pounds could be 

 hauled on the broad tires with the same draft required for 2,000 pounds on the 

 narrow tires. 



" * * * * * * ='= * * Summing up all the tests on dirt roads, it appears 

 that there are but three conditions on wliich the broad tires draw heavier than the 

 narrow tires, viz.: (1) when (he road is sloppy, muddy or sticky on the surface and 

 firm or hard underneath; (2) when the surface is covered with a very deep, loose 

 dust and hard underneath; (3) when the luud is very deep and so sticliy that it ad- 

 lieres to the wheels on both kinds of wagons. It appears that the dust must b> 

 extraordinarily deep to show a higher draft for the broad than for the narrow tires. 

 The three conditions just named, therefore, are somewhat unusual and of compar;i- 

 tively short duration. Through a majority of days in the year, and at times when 

 the dirt roads are most used, and when their use is most imperative, the broad tired 

 wagons pull materially lighter tliau the narrow tired wagons. 



"IV. A large number of tests on meadows, pastures, stubble lands, corn ground, 

 and plowed ground in every condition, from dry, hard and firm to very wet and soft, 

 show without a single exception a large difference in draft in favor of the broad 

 tires. This difference ranged from 17 to 120 per cent. 



"V. It appears that six inches is the best width of tire for a combination farm 

 and road wagon and that both axles should be the same length, so that the front ami 

 hind wheels run in the same track." 



It is not within the purpose of this bulletin to speak at lenght of the eifect of the 

 habitual use, upon the one hand, of broad tires and on the other narrow ones, 

 on the ordinary dirt roads of the country. The point cannot be passed, however, 

 without calling attention to the fact that the deep ruts common to sections where 

 narrow tires alone are used, are rare or entirely wanting in those sections where 

 broad tires prevail. 



INFLUENCE OF THE POSITION OF THE LOAD ON THE WAGON UPON THE 



DRAFT. 



On October 19, a comparison was made between the draft of the wagon when the 

 load was equally distributed upon all four wheels and the draft of the same wagon 

 when the load was piled over the rear axle. Two trials were made in each case. 

 The draft of the wagon when the load was equally distributed was 149 pounds, 

 when almost entirely upon the hind wheels, 147 pounds, practically the same. These 

 trials were made on a hard gravel road. A few days later upon a June grass sod 

 the average of two trials in each ca.se shows that with the load distributed the 

 draft was 167 pounds, with the load on the front wheels, 294 pounds, upon the rear 

 wheels, 289 pounds. These results seem to show that where the road is firm and 

 smooth it is immaterial whether the load is evenly distributed over the four wheels 

 or not, but where the ground is soft the draft is increased if the weight is very 

 largely upon the front or hind wheels. 



THE INFLUENCE OF POINT OF ATTACHMENT OF THE POWER UPON 



THE DRAFT. 



These tests were made upon a gravel road in tlie first case level, and, in the second, 

 with a grade of six feet to the hundred. In the first case where the dynamometer 

 was attached in such a way as to bring the whiffletrees in a normal position the draft 

 was 188 pounds; when the power was applied at the end of the tongue, nine and one- 

 half feet ahead of the ordinary point of attachment, the draft was 174 pounds. 

 AVhere the load was drawn up the grade mentioned, when the whiffletrees were in 

 the ordinary position the draft was, as the average of two trials, 366 pounds; when 

 the horses were hitched to the end of the tongue as before the draft was 379 pounds. 

 These trials do not show a marked difference in draft Avhich can be attributed to the 

 dilference in point or method of attachment. 



