132 



SCIENCE OF AGRICULTURE 



Part II. 



2759. HapS'jii's stop drag for carriages going 



doivn hill (figs. 388, 389, and 390.) con- 

 ^Sy sists of five or more 

 pieces of wood, 

 " united onthe out- 

 side by a strong 

 jointed iron hoop ; 

 the wood pressing 

 upon the nave of 

 the wheel. The 

 first, a fixed pivot 

 (a), from the hoop, 

 is fixed to the under 

 side of the frame of 

 the cart ; from the 

 other extremity of 

 the hoop of the 

 brake proceeds a 

 bar (b), which slides 

 through the plate 

 or socket (c) fixed 



to the side of the cart frame ; a vertical perforation is made through the bar (b), 

 just behind the plate, to receive the pin (d), which is likewise chained to the shaft : this 

 pin, so placed, prevents any force applied to the chain from tightening the brake on the 

 nave of the wheel. Fig. 389. represents the interior of a wheel on level ground, the 

 nave surrounded by the brake, which, by its own gravity, is hanging loose, leaving the 

 wheel perfectly free. Fig. 390. shows a wheel on a declivity, the chain drawn tight by 

 the pressure of the breeching on the horse ; the brake, of course, closely surrounding 

 the nave, and forming an effectual drag. Fig. 391. is a bird's-eye view of the whole 



apparatus, exhibiting the framing of the cart, the 

 shafts, wheels, and brakes ; the chains also are 

 shown, passing from the bars on each side, each 

 round a horizontal pulley on the shaft, and 

 attached to the ends of the breeching. Thus it is 

 evident that, when a cart, furnished with this 

 drag, is going down hill, the load, pressing the 

 breeching against the horses, draws the brake 

 tight by means of the chain, and produces a 

 friction on the nave proportioned, in some measure, 

 to the declivity. When backing upon level ground, by inserting the pin (fig. 388. d) 

 through the bars of the brakes, the wheels will be kept free. Tin's drag is to be applied 

 to the naves of the carriage wheels, with a chain attached, fastened to the breeching of 

 the horse, and a small pin on each side of the shaft is to go into the hole of the bar of 

 the drag. If one of the pins be taken out, one wheel will be dragged and the other not. 

 By leaving out both pins, the two wheels are dragged in going down hill, by the 

 breeching bearing against the horse. The wheels will revolve round on a level road, and 

 in going up hill undrag themselves. When the wheels are braced, two or three tons' weight 

 have very little pressure on the horse in going down hill. If two loaded carts should 

 meet on a narrow hill, by unhooking the drag-chain from the breeching, and hooking it 

 to the tub-chain (back chain), the horse can be put back with the greatest ease and safety. 

 When the horse is put back against the hill, the two pins must be put in the bars of the 

 drags. The drag consists of a wooden brake, applied round the nave of each wheel, in 

 pieces which are encircled and connected by a jointed iron plate. The small bar attached 

 to one end of this brake slides freely through a corresponding hole in a plate fixed at 

 right angles to the shaft : a hole is drilled through this sliding bar, for the purpose of 

 admitting a pin or forelock, chained to the shaft. To each end of the breeching is 

 attached a chain, which, passing through a horizontal sheeve, or pulley, on the upper 

 surface of each shaft, is ultimately fixed to the bar of the drag. While the bolts or fore- 

 locks remain in the holes behind the perforated plate before mentioned, it is evident the 

 brake cannot tighten upon or drag the wheel ; but, on either of those pins being 

 removed, the wheels become immovable." (Smith's Mechanic, vol. ii. p. 322.) 



2760. Kneebone 's drag for two-wheeled carriages (fig. 392.) is composed of a piece of 

 wrought iron, curved to the exact form of the circumference of the wheel, with a chain, 

 to be fastened to the near shaft, to keep the drag properly under the wheel. When 

 the drag is out of use it may be hung on hooks, at the under part of the tail of the 

 cart. The weight of this drag is usually from sixty to eighty pounds. " This simple 

 contrivance has never failed to be effectual in retarding carts, or any two-wheeled car- 

 riages, while descending hills, taking off the great burden from the shaft horse, and 



