606 



REroiiT — 1884. 



only one movable point rail, the other being fixed like a frog point ; but 

 this is not a good arrangement. If the movable point rail is placed inside 

 the cnrve diverging from the main line, then, when it is set right for the 

 diverging lino, it acts not as an ordinary point rail, but as a guard rail, 

 for which it is not suitable; also, no matter which way the switch is 

 placed, the snppoi-t to the treads of the wheels is not as much as two 

 point rails giv?, and the stock rail alongside the fixed point wears out tlio 

 same as a wing rail in a frog wears out at the frog point. One of the 

 greatest dangers with the sjdit switch — tliat of loose wheels working in 

 to catch the end of the open point — is doubled in the single point switch, 

 for a loose wheel will catch as easily on the end of a fixed ])oint as on an 

 open point, and when the point in such switches is open, there are two 

 places where there is a liability of trouble. In tliis connection it would 

 be well to say that split switches should always be made trailing if possil)Ie ; 

 never facing t\w travel if it can be avoided. On single track lines. th 

 travel in both directions, it is not feasible to carry out this precai. -u; 

 but on double track lines the matter should never be overlooked, as it may 

 pi'cvent serious accidents. If a trailing switch be operated by a sprinij 

 or weiglit, so that, in case the switch is wrong for an approaching train, 

 the flanges of the wheels advancing from the fixed rail ou to the movable 

 point rail can overcome the resistance and move the points into their 

 proper position, thus avoiding a derailing of train, then the switeh 

 becomes a self-acting ' safety switch.' 



!Mr. AVilliam Lorenz, who has for n long time been chief engineer of 

 the Philadelphia and Heading Railroad, designed a simple and practicable 

 form of self-acting split switch, with a s{>ring securely holding the points 

 against the stock rail, so that the switch was safe for all trains approachinir, 

 facing the switch, at the same time that it was self-acting as a tniiliriL;' 

 switch. His switeh being the tyjie of all of these, his name is deservedly 

 attfiched to them, and they are known ar* the ' Lorenz Safety Switch.' 

 Fig. 2, Plate VIII., shows the Pennsylvania Steel Company's improved 

 pattern of this switch. The general arrangement is the same as already 

 described, except as it regards the spi-ing, which is steel, double coiled, 

 and is generally arranged in a yoke on the side of the front connectin;: 

 bar, where it can bo conveniently reached for adjustment. The length 

 of the points is 15 feet, and the throw is 'Mj inches, the switch stand 

 throwing 4 inches to give proper compression to the spring. In the 

 original Lorenz pattern the points were usually made much longer, even 

 up to 30 feet. 



A shorter pattern of safety switch is made for yard service, the point 

 rails being as short as seven feet six inches, with a flange way at the heel 

 of only two inches. 



The Pennsylvania Steel Company also make an automatic switcli 

 stand, which, by the combined operation of a weighted lever and gearinjr, 

 holds the switch with a solid rigid throw, and renders it absolutely sati' 

 for all ' facing ' trains, at the same time giving a signal indicating the 

 po.sition of the point. It also acts automatically as a safety switch for 

 trains trailing over it from either track. When acting in the latter wav. 

 the first pair of wheels over the switch set it right, so that the remaining: 

 wheels do not have to open the switch each for themselves, as in the safotv 

 switch with springs. 



In Wharton's Patent Switch, the great principle is always to ])re- 

 serve an unbroken line in the main tracks, under all circumstances, and 



