The Works Of Messrs. Schneider And Co.

DISAPPE ARING CUPOLA FOR 5.7 CENTIMETRE GUN. 319 The fixed centring ring and the turret support are of cast steel ; the former is embedded in the top part of the pit, the latter resting on a central foundation at the bottom of the pit. All the required accessories for ventilation, for the ammunition service, for removal of the gun, &c., are carefully designed for the work they have respectively to fulfil. The disappearing mechanism consista of a balancing device and a driving winch, the force of recoil being utilisée!. The central column on which the turret rests is furnished by a plate-chain, which turns on an eccentric, so that the height of the turret varies according to the radius around which the chain is rolied, the largest radius corresponding to the position of the turret in battery. The counterweight that balances the lurret is carried by tvvo platechains that surround eccentrics of same shape as the turret eccentric, but keyed inversely on the same shaft, the maximum radius corresponding to the greatest height of the counterweight. The counterweight is calculated to balance the turret exaetly in its medium position. When the turret is up, and the gun run out for firing, the radius round which the turret turns is the maximum ; that of the counterweight chains is the minimum radius ; the turret has a prépondérance which tends to run it clown. The turret is exaetly balanced by the counter- weight when it is approximately in the middle of its travel. When the turret is completely down, the position of the chains on the eccentrics is reversed, and the counterweight has a prépondérance which tends to run up the turret. To start each. manœuvre, a certain amount of work is required, equal to the résistance caused by friction of the varions parts, to bring the turret to its extreme positions. This is given by the driving or starting winch. This consista of a set of gearing working a rack; this acts in conjunction with a pinion keyed on the eccentric shaft. A crank-shaft forms part of the system, and its dimensions are such that for a complété movement of the turret the rack slightly oversteps the upper and lower dead-points, and strikes against wood Blocks. As at both ends of the travel, the prépondérance tends to cause the rotary action of the shaft to continue, the whole system stops at the right moment, and it is only necessary to act on the winch crank to pass the dead-points, and cause the system to act of itself. The parts forming the disappearing mechanism are few in nuinber, and of strong rnake ; one man can efiect the complété running- down of the turret in three seconds. The turret reaches the ends of its travel with slackened speed and without shocks ; the action is automatic, and requires no power. It is served by two men, one gunner and one assistant. Weight of gun ,, projectile ... „ recoiling mounting Maximum recoil Range of elevation Time i’equired from one complété range of elevation to the other ... Lateral training Time required for one complété revo- lution of the turret Time required for withdrawing the gun and running down the turret Time required for resuming the fii’ing position Time required. for dismounting and reniounting the gun 180 kg. 2.720 kg. 210 kg 100 mm. — 6 deg. to + 6 deg. 4 secs. Through 360 deg. 60 secs. 12 secs. 397 Ib. 6 Ib. 463 Ib. 3.937 in. - 6 deg. to + 6 deg. 4 secs. Through 360 deg. 60 secs. 12 secs 10 secs. 25 min. 10 secs. 25 min.