CH. V BRAKE 8 I 



The best leather for this purpose is old belting, 

 which is flat and somewhat oily. Pieces of old 

 india-rubber tires, fastened on a wooden block, are 

 much used by French builders and make a good 

 brake ; this is shown in Fig. 42. The best material, 

 however, is a tough wood, like chestnut, used alone ; 

 oak is too hard and squeaks almost as loudly as 

 iron. The soft wood wears, but it can be easily 

 replaced. The arm should terminate in an iron 

 socket, of the form shown in Fig. 42, the hollow 

 beinor somewhat smaller at the 

 bottom than at the top, and the 

 block being- made to fit it. A 

 dozen blocks can be made at a 

 time by any carpenter, and kept 

 ready for use. When a block is 

 worn, it can be knocked out by a blow from below, 

 and the new block dropped into its place ; no other 

 fastening being necessary. Of course, both blocks 

 should be renewed at the same time, so that they 

 shall bear equally on both wheels. 



Blocks of this shape in solid rubber can be bought 

 ready made, from the manufacturers. 



The handle of the brake moves past a toothed 

 rack, and when the block is pressed against the 

 wheel, a sharp projection on the side of the handle 

 engages with one of the teeth and holds the brake 

 against the wheel. To release the brake, the 

 handle is pushed outward, its length giving it 

 enough spring for that purpose, and the projection 



