CHAPTER VI 



DRIVING AND HARNESS 



247. On Driving. — The subject of draught is one 

 that affects our servant the horse very greatly, 

 and therefore it is only fair to consider this 

 matter in detail. The subject is not understood 

 to the extent it should be, considering that 

 99 per cent, of the horses in the cities are draught 

 horses. This misunderstanding exists because 

 drivers are apt to allow things to go on in the 

 slipshod vi^ay they have been used to in the past. 

 Some books written on the subject are full of 

 theory which could never be put into practice. 

 Mechanics seems to be less understood in this 

 branch than in any other. In considering the 

 load that a horse can draw we must consider 

 three factors : the force and the method of apply- 

 ing this force ; the vehicle and the weight 

 carried by it ; and the track on which the vehicle 

 is to move. The former refers to the type of 

 horse and the type of harness. From the horse's 

 point of view, and from a pecuniary point of 

 view, we must aim at getting the most work 

 out of a horse with the least exertion, i.e. least 

 waste of energy. This is the principle upon 

 which all engines are made, but I am sorry to 

 say upon which horsed vehicles are seldom 

 constructed. 



248. We will first consider how a horse draws 

 his load. He throws his weight forward, and 

 then temporarily removes the support under the 

 foremost portion of his body (i.e. his forelegs), 

 and thus allows the weight of his body to be 

 supported by the hindlegs, which will be in 

 compression ; the traces of the vehicle will then 

 be in tension. Strictly speaking, then, the 

 weight of his body draws the vehicle forward 

 primarily. As well as this, the muscles of all 

 forelimbs advance the body forward on the 

 limbs, so that the draught power of a horse is 

 much greater than his weight. A horse weigh- 

 ing 1,500 lb. can draw up to ten tons on a smooth 

 road for a short distance. We will first consider 

 the best place to attach the traces to. It has 

 been stated that 50 per cent, of the power of 

 draught horses is wasted through want of know- 

 ledge of the theory and practice of draught. I 

 can quite believe it. The load that a horse can 

 pull, i.e. the resistance that he can offer to a 

 load, depends on (i) his own weight, (2) his 

 grip upon the road, i.e. resistance between his 

 feet and the road, (3) his length and height, i.e. 



the lengths of the levers acting upon the load, 

 (4) the direction of the trace, i.e. the direction 

 of the acting force, and (5) his muscular 

 strength. 



P. 32, Fig. 1, shows the forces acting upon 

 the horse. If the trace ab is horizontal, and the 

 vertical weight of the horse on his forelegs is 

 AC, the resultant force, when the horse is in 

 draught, will be ad. Now, let us attach the 

 trace as in Fig. 2, a'b' ; then a'c' still represents 

 the horse on his forelegs, but the resultant force 

 is a'd', and with the same load the horse has 

 an extra force acting upon his collar ; hence, 

 theoretically, the horse's traces exert least force 

 upon the collar when they are horizontal. In 

 practice, however, there are two factors that 

 cause a slight modification of this : firstly, by 

 lowering the traces slightly we increase the 

 resistance between the horse and road, and, 

 secondly, we diminish the liability of the collar 

 from slipping up the shoulder. This slipping 

 is common if the shoulder slopes very much. 

 Hence the necessity for draught horses' shoulders 

 being as upright as possible. [See P. 296, 36c, 

 h, ilb, 105c.) With an almost vertical shoulder 

 we would have the ideal draught shoulder. The 

 trace should act at right angles to the shoulder 

 to avoid friction on that part, and, when nearly 

 horizontal, causes least friction. 



249. Another way of looking at this question 

 is this. A horse is required to draw the load 

 horizontally along a level road, but if we have 

 the trace attached just behind his heels he is 

 partially lifting up the front of the load, and is 

 therefore wasting a great deal of energy. Hence 

 the lower the traces the more energy will be 

 wasted, and the greater will be the weight 

 brought upon the horse's forelegs, and therefore 

 the quicker will his forelegs be worn out. 

 Again, the lower the traces the more the collar 

 is drawn down, so that the neck of the collar 

 rests on the horse's neck. This liability increases 

 as the horse's shoulder is more upright. The 

 above points are theoretically correct, and are 

 practically correct, too. I have taken the trouble 

 of going minutely into this matter with owners 

 of draught horses who use sleighs with traces 

 attached low down. {See P. 35rf.) Messrs. Elias 

 Rogers, the largest coal dealers in Toronto, told 

 me that the above points were absolutely correct ; 



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