298 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL, 



fOcTOBEB, 



eilee. The cylinder is stopped on risini; to the top by a wood 

 bhick fi.xed on each of the four guide-posts F, I", wliicli stop the 

 platform at the level of the top stajre Ci, G. 



P, is a cast-iron pipe 7 inches inside diameter, which conveys 

 the compressed air from the air-main, and the pipe Q, of tlie same 

 size, carries it into the cylinder, passin;; down to the bottom of the 

 well between the cylinder and the side of the well, and rising up 

 the centre of the cylinder; the end of the pipe at R, is open and 

 stands above the level of the water. 



The valve S, regulates the admission of the compressed air into 

 the cylinder when the platform is raised, and also lets out the air 

 from the cylinder when it is lowered. This valve consists of a 

 jilug or deep piston, sliding in a vertical bored cylinder of the 

 same diameter as the air-pipe, which is closed at the top and open 

 at the bottom. When the plug is in the lowest position, as shown 

 in fig. 1, it closes the bottom of the cylinder, and the communica- 

 tion is opened between the pipes V and Q, and the compressed air 

 passes into the air-cylinder A, and raises it, with the platform D, 

 by the pressure of the air upon the top of the cylinder and upon 

 the surface of the water; the pressure of the compressed air is 

 2^j lb. per square inch, and the water is depressed inside the cylin- 

 der to T, and raised toU outside the cylinder, making a difference 

 of level of 5 ft. 4 in. \V'hen the platform is requii-ed to be low- 

 ered, the plug-valve S, is drawn up to the top, as shown in fig. 2, 

 closing the pipe P, that admitted the compressed air, and leaving 

 the pipe Q, open to the external air to discharge the compressed 

 air from the cylinder A; this discharge is accelerated by opening 

 the escape- valve B, at the top of the air-cylinder by means of the 

 foot-lever C. 



The total pressure of the compressed air against the top of the 

 air-cylinder is 3J tons; and deducting the unbalanced weight of 

 the cylinder and platform (i-ton), this gives an available lifting 

 power of 3 tons. The load of materials raised varies according to 

 the working of the furnaces, and the average load of materials 

 raised each time is l^tons, exclusive of the barrows and men, or 

 about 2 tons gross weight. The lift is raised 10 times per hour 

 during 20 hours in each day of Si hours, or once in 3^ minutes; 

 and the totsJ weight of materials raised each day is about 500 tons. 

 The time of raising the platform from opening the inlet valve to 

 reaching the top is from 50 to 70 seconds, according to the load in 

 regular work ; and the time of lowering the platform is from 30 to 

 50 seconds, according to the degree of opening of the escape valve 

 on the top of the air cylinder; the empty platform can be raised 

 in 45 seconds, and lowered in 25 seconds, with the present size of 

 apertures. 



In raising the platform the inlet- valve is kept full open nntll 

 the platform arrives at 14 inches distance from the top, when it 

 catches a lever which gradually draws up the plug of tlie inlet- 

 valve, so far as nearly to close the pipe leading to the air-cylinder; 

 this checks the moving power and causes the velocity of the plat- 

 form to be so much retarded by the time it arrives at the top, that 

 the platform stops dead against the wood blocks without any con- 

 cussion being felt. The platform is held firmly up to these stops 

 by the pressure of the air as long as may be required, without any 

 recoil, nJid without requiring any catches to hold the platform, as 

 it cannot descend in the least unless the air is allowed to escape 

 from the cylinder, and the supply from the air-pipe keeps it full 

 in tlie case of any leakage taking place. 'W^hen the platform is 

 raised empty, a wood block turning on a pivot is slipped by the 

 foot under tlie lever that closes the inlet-valve, so as to begin 

 closing the valve sooner; this is adjusted according to the velocity 

 of the ascent of the platform, and regulates the lifting power so 

 as to prevent any concussion on stopping at the top of the ascent. 



AVhen the platform arrives at the top, the men who go up with 

 the barrows wheel them off to discharge the materials into the 

 several furnaces; and as soon as the empty barrows are brought 

 back, the platform is lowered by drawing up the plug of the inlet- 

 valve to the top, which shuts off entirely the supply of compresned 

 air, and opens the exit below the plug for the air in the cylinder to 

 escape. This is done by the men on the platform at the top by 

 means of a ro<l from the valve cari-iod up the framing; and the 

 escape-valve on the top of the cylinder is then opened, and kept 

 open till the platform is near the bottom, when it is closed, and 

 the velocity of the platform is so much checked before stopping, 

 that scarcely any concussion is felt at 8toj)j)iug; it can e;isily be 

 stopped without any concussion. 



Tlie velocity of the platform is also gradually checked in de- 

 scending by the gradual immersion of the cylinder in the water, 

 which reduces the unbalanced weight of the cylinder. The total 

 loss of weight of the cylinder when at its greatest immersion in 

 the water is i-ton, which reduces the effective unbalanced weight 



of the cylinder and platform from ^^-ton to nothing; but the 

 weight of' the four chains, amounting to f|-ton, is added to the 

 balance-weights at the beginning of the descent, and is transferred 

 to the platform at the end of the descent, and the result is that 

 the moving power causing the descent of the platform is reduced 

 j-ton during the descent, being about f-ton at starting and g-ton 

 at stopping; this moving power can be altered as required, by 

 altering the balance-weights. 



This lift was originally constructed to work only two furnaces, 

 and the air pipe was only 5 inches inside diameter, and the time of 

 raising the platform was usually 140 seconds; when the other two 

 furnaces were added it became necessary to add a second air pipe 

 of the same size, for the purpose of working the lift twice as fast; 

 one pipe only is shown in the accompanying drawing, equal in area 

 to the two actually employed. AV'hen the lift was constructed it 

 was found that the well could not be made sufficiently water-tight, 

 on account of a slight disturbance in the strata from the getting of 

 the neighbouring mine, and an outer cylinder of similar construc- 

 tion to the air-cylinder, was consequently sunk into the well ; this 

 outer cylinder having a close bottom, and holds the water in which 

 the air-cylinder works, like the tank of a gasometer. 



The quantity of air blown into the cylinder each time of raising 

 it is 1,128 cubic feet, and the total quantity per day of 24 hours is 

 300,900 cubic feet, or about 12 tons weight of air; the total quan- 

 tity of air blown by the blast engines is 16,185 cubic feet per 

 minute, and 23,300,400 cubic feet, or about 780 tons weight of air 

 per day of 24 hours. The proportion of the total blast that is 

 used by the lift is therefore as 12 tons to 780 tons, or ^ of the 

 whole, and consequent ^V part of the total power of the hlowing 

 engines is employed in working the lift; there are two blowing 

 engines employed The pressure of the blast is 2j lb. per square 

 inch, and the total engine |iower is consequently 165-horse power; 

 and the air consumed by the lift being ^^ of the total blast, it 

 follows that -irs of 105, or 2i-horse power, is the power that is 

 actually employed in working the lift; this power being a con- 

 stant power acting during the whole day instead of acting merely 

 at the times when the lift is rising. The actual power required to 

 elevate the lift, with the average gross load of 2 tons on the plat- 

 form, or 2j tons total weight, including the average unbalanced 

 weight of the cylinder and platform, raised 44 ft. 6 in. in 70 

 seconds, is 6-horse power; the greatest power employed being 

 3J tons raised that height in 70 seconds, which amounts to 9-horse 

 power, and the least is 5-ton raised in 45 seconds, amounting to 

 1-horse power. Thus it appears that the work of 6-horse power 

 occurring at intervals, is performed by a power of 2J-horse powej 

 constantly acting. 



The total consumption of coal-slack by the blowing engines is 

 about 13 tons per day of 24 hours, consequently the expense of 

 working the lift is -^ part of this, or 4 cwt. of coal-slack per day, 

 costing about 5rf. per day; and as this lift raises 500 tons of ma- 

 terials per day, it follows that 100 tons are raised 44 ft. 6 in. high 

 for Id., or 4,450 tons are raised 1 foot high for Id. The quantity 

 of air required to fill the cylinder of the lift is 1,129 cubic feet, 

 and the total contents of the blowing cylinders for one double 

 stroke is 1,058 cubic feet; consequently, an increase in the rate of 

 the engines of one stroke per minute is sufficient to raise the lift 

 in 70 seconds, without diminishing the supply of air for the blast 

 of the furnaces. 



These two circumstances cause an important economy in work- 

 ing this pneumatic lift; a small power constantly acting is sufficient 

 todo the work, and the sudden application of this power concen- 

 trated into a short time causes but a small increase in the rate of 

 the engine. The total cost of this lift was about 500/.; and the 

 cost of an inclined plane lift, including the engine for working it, 

 would be about double that amount. 



This pneumatic lift has been in constant work for the last nine 

 years, and no accident or stoppage has occurred with it, except 

 that the chain of one of the balance-weights broke once; the plat- 

 form stopped with a very trifling fall, and was held in its position 

 by the pressure of the air; no damage was caused, and the lift was 

 got to work again within an hour's time. The only repairs that 

 have been required since it commenced working, are the renewal 

 of the chains of the balance-weights and repair of the pulley- 

 bearings: the set of chains can be taken off and replaced whilst 

 the lift is standing during the dinner hour, without causing any 

 delay to the work. This is an important advantage, as it is essen- 

 tial to ensure a continued supply of materials to the furnaces, 

 and to avoid any risk of stoppage for repair of the lifting ma- 

 chinery. 



The platform in this pneumatic lift cannot fall quicker than the 

 1 time in which the whole body of air can escape, amounting to 



