336 RAILWAY CONSTRUCTION. 



position. The stop-lever must then be set back to raise the 

 stops and hold the gates secure. The train-signals will be 

 retained at danger by the interlocking gearing, and cannot be 

 lowered until the gates are set back again across the public road, 

 and the gate-stops raised. 



It is frequently urged that the celerity with which me- 

 chanical gates can be swung round and closed across the public 

 road, is in itself a source of danger, and that persons preparing 

 to cross the line might be struck by a moving gate, unless they 

 received a distinct warning that such closing was about to take 

 place. There is no doubt persons have been struck by such 

 gates when closing across the road, and heavy claims for injuries 

 have been decreed against railway companies, who were unable 

 to prove that the man in charge had called out or given warn- 

 ing before moving the gates. To ensure that due and undeni- 

 able warning shall always be given, a firm of signal-makers 

 have patented an appliance by which a powerful electric gong, 

 fixed on the top of a tall post close to the gates, is sounded 

 automatically by the gate machinery itself, and before the gates 

 actually commence to move. As previously described, the pulling 

 over of the lever to lower the gate-stops is the first operation to 

 be performed whenever it is necessary to change the position of 

 the gates, and it is the pulling over of this lever which actuates 

 the apparatus, by bringing two electric points into contact, and 

 thus starting the ringing of the gong or alarm. The gong con- 

 tinues to sound until the gates are moved over, the gate-stops 

 raised, and the stop -lever put forward again into its normal 

 position. The arrangement is very simple and very effective, 

 and being purely automatic must work as regularly as the stop- 

 lever. The tone and volume of the gong can be varied to suit 

 circumstances. The public soon become familiar with its sound, 

 and recognize its meaning. 



Figs. 509 and 510 give sketch plan and elevation of a set of 

 mechanical gates for a public road level crossing on a double 

 line of railway. The signal-cabin should be placed within a few 

 yards of the gates, to enable the man in charge to have a good 

 view of the persons and vehicles passing over the roadway. 

 The underground gearing for working the gates and stops, must 

 be protected by iron or wooden casing. The swinging portion 

 of the wicket gates is closed, and held by a separate lever. The 

 gates shown on the sketch are for a crossing on the square, but 



