. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. essing operation. Thevalves are all worked by one man by means of rocking shafts, and suitable means are provided toprevent the pistons E and F from coming into contact with the ends of their cylinders. The cotton press itself has two cylinders with the rams S S working upwards, Fig. 1480 ; theseraise a crosshead, to which are attached strong wrought-iron links carrying the following table orplaten; the casting on which the cylinders rest forms the top platen, and the water being forcedinto the cylinders r
. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. essing operation. Thevalves are all worked by one man by means of rocking shafts, and suitable means are provided toprevent the pistons E and F from coming into contact with the ends of their cylinders. The cotton press itself has two cylinders with the rams S S working upwards, Fig. 1480 ; theseraise a crosshead, to which are attached strong wrought-iron links carrying the following table orplaten; the casting on which the cylinders rest forms the top platen, and the water being forcedinto the cylinders raises the lower platen on which is placed the cotton bale, and compresses thelatter to the required density. The steam cylinders are each 56 in. diameter; the pressure of steam used is 80 lb. a ; the area of each piston being 2463 sq. in., this multiplied by 80 gives 197,040 lb. totalpressure on one piston. The smaller hydraulic plunger is 9| in. diameter or 7466 sq. in. area; 197 040and _. „„ = 2640 lb. a sq. in. as the pressure on the plunger. The press has two rams, each. jrC!.n ^ a 74-66 3 c 2 766 HYDRAULICS. 22 in. diameter, the collective area of which = 7G0 sq. in.; and 760 sq. in. x 2G40 lb. si sq. ineh= 2,006,400 lb. or 895 tons total pressure on the bale, with 80 lb. a sq. in. steam pressure in theboiler. With a pressure of 3 lb. a sq. in. in the steam cylinder all the weight and friction ofparts are overcome; and since each lb. a sq. inch of steam pressure represents a total pressure of2,006,400 -j- 80 = 25,080 lb. on the press rams, the total frictional resistances amount to only75,240 lb., or say 35 tons approximately. Deducting this from the total pressure of 895 tons, thereremains 860 tons total effective pressure on the bale. It must not be forgotten moreover, that apart of the dead weight raised is utilized in returning the pistons and rams, after each pressingoperation is over. Fig. 1483 is of the packing employed for the rams, Fig. 1469; Fig. 1484,
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectenginee, bookyear1879
