1842.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



35 



Suppose DOW the pin of the lever S (moving the piston rod w, by 

 means of the lever R on the shaft P), stands in the point 2, then the 

 engine would have no lead, but as the friction between the eccentric 

 and its ring, wanU to take the ring with the eccentric, it will go round 

 with it till the pin of the lever S has come in the point 1, when it will 

 have the position wanted for the lead. When the engine is reversed 

 the eccentric ring will turn with the eccentric till the pin of the lever 

 S has arrived in the point 3, which will then give the position re- 

 quired for the lead of the reverse of the engine. The eccentric line 2 

 of the circular slot of the other eccentric ring for the adjoining ma- 

 chine, stands in an angle of 90 degrees to the centre line of the circular 

 slot of the other eccentric ring, through which the lever T and Q, 

 works the piston rod of the adjoining machine. 



The levers R and S, and T and Q, can work on a fixed shaft P, by 

 means of loose bushes, or the shaft P has to be divided in two, and 

 then the levers can be keyed or forged on the shaft. 

 We are, Sir, 



Your obedient servants, 



H. AND P. 

 15, Bedford Street, 

 Chorltoii'Upon-Shedlock, Manchaler. 



BRAITHWAITE'S APPARATUS FOR DISCONNECTING THE PADDLE WHEEL OF STEAM VESSELS 



FROM THE ENGINE. 



Fig. 1.— Side view. 



Fig. 2. — Section. 



In' our last number we gave a description of aa 

 apparatus for connecting ana disconnecting the paddle 

 wheels of marine engines. We have now another 

 apparatus to describe, which appears equally as effec- 

 tive, and very simple in its action. It has Utely been 

 tried at Woolwich, on board H. M. steam vessel 

 " Kite," and found to answer the purposes intended ; 

 it is the invention of Messrs. Braithwaite, Milner 

 & Co., of the New Road. The annexed drawings ami 

 description fully explain its action. 



A, Paddle wheel shaft. 



B, Crank pin. 



C, Cast iron disc keyed to shaft. 



D, Brass friction band fixed by screws to the ex- 

 ternal wrought iron rim G. 



E^ Brass friction break. 



F, Iron key wedge, head, 4"xli". 



G, External rim, 2i"X6" of cast iron keyed to 

 crank pin. 



For the purpose of disconnecting the crank, it is 

 only necessary to drive out the key, which imme- 

 diately relieves the brass break E from pressing 

 against the cast iron disc, and allows either the ex- 

 ternal rim and the crank or the internal disc and shaft 

 to revolve independently of each other. 



For the purpose of connecting the apparatus, it is 

 only requisite to drive in the keyed wedge, which 

 forces the brass break E against the iron disc. 



ON THE PROPORTIONS OF STRAPS FOR DRIVING 



MACHINERY. 

 Sir — Although the subject of the present communication may, to 

 some of your readers, appear of a nature too frivolous, or not alto- 

 gether adapted to the character of your journal, it is still a subject of 

 the must frequent occurrence to the practical mechanic, and probably 

 that which receives the least of his attention. However, I cannot 

 recollect ever seeing in print any rule or proportion relative to the 

 breadths of straps for driving. Probably this is owing to the great 

 variety of circumstances to which straps are subject, and which difler 

 more or less in almost every case ; such for instance as horizontal, 

 vertical, long, short, open, and crossed straps, the pliability of the 

 leather, and so on. A horizontal stmp is better than a short one, and 

 a long horizontal strap will always perform its work with much 



greater ease than a short one. A crossed strap, whether horizonta 

 or vertical, is known to be more powerful than an open one, &c. But 

 I will not pretend to give any rule for determining the power of a 

 strap ; the object of tbis communication is, to direct your attention 

 to a combinatwn of str.ips. 



In a combination, that is, a number of straps one working another 

 over drums and pulleys for multiplying the number of revolutions, it 

 is very common for one or two of the straps to be constantly breaking 

 or giving way, while the others work for montlis and months without 

 requiring the least repair. The straps which most frequently gel out 

 of repair are generally those which tr.ivel at the greatest velocity, ami 

 it is to the rapidity of their motion that their frequent breaking, Sic, 

 I is generally attributed ; but 1 am inclined to think that this is not the 

 real cause, in proof of which I will here give an instance of a very 

 recent occurrence that came under my notice. 



