. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . he stream rushing out roundthe upper valve V, but mainly by theupward pressure of the issuing currentagainst the curved shield >S fixed onthe valve-stem. In working this formof ram it has been found that accurateadjustment was required to suit thehead or fall of the driving-water; andalso that the shock was too great forthe safety of small rams. In the ram shown in Fig. 4 thetwo escape-valves T and E are ar-range
. Modern mechanism, exhibiting the latest progress in machines, motors, and the transmission of power, being a supplementary volume to Appletons' cyclopaedia of applied mechanics . he stream rushing out roundthe upper valve V, but mainly by theupward pressure of the issuing currentagainst the curved shield >S fixed onthe valve-stem. In working this formof ram it has been found that accurateadjustment was required to suit thehead or fall of the driving-water; andalso that the shock was too great forthe safety of small rams. In the ram shown in Fig. 4 thetwo escape-valves T and E are ar-ranged to pass up freely through theirseats, and are stopped by an air-cush-ion at the top. The waste water near-ly all escapes at the upper valve F,small outlets only being provided inthe lower valve E for permitting sandto escape if any should be carriedinto the machine. The closing iseffected mainly by the upward press-ure of the issuing stream against thecurved shield S. When the valves areshot upward in closing, the shield en-ters the air-chamber above it, in whichit fits as a piston, and the momentumFigs. 3, hydraulic ram. is thereby checked without the least. 276 ENGINES, MARINE. shock air-cock is inserted in the top of the air-chuniher at /., for regulating the amountof re^^tancf offered bv the air-cushion. Additional weight, if reciuired for opening the valves,is added on the top of the valve-stern at K; it is found, however, that the higher the deliveryhead the less is the weight required, because of the reflux. Shifting valves were at first ap-plied but seemed unnecessarv. Kams arranged in this manner work without noise or jar andLive a hi-li efficiencv for forcing four to five times the height of the propelling head, and areSuitable ni most cases for irrigating purposes; but wlu-n the resistance is increased the elas-tic blow or percussive impulse of tlie current is not enough to raise the check-valve t againstthe increased area caused by its lap. u- u ti,
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Keywords: ., bookcentury1800, bookdecade189, booksubjectmechanicalengineering
