104500, Their principal use is to give a sharp jar to the drill on the upstroke so that the bit is dislodged if it has become jammed in the rock.
2
104500, This flying machine consisted of a light frame covered with strong canvas and provided with two large oars or wings moving on a horizontal axis, and so arranged that the upstroke met with no resistance while the downstroke provided the lifting power.
3
104500, Click to start the upstroke Click on the upstroke to select the POWER level of the shot.
4
104500, The air inside is compressed in consequence and during an upstroke of the piston this air tends to regain its original volume and so expels the water, thus bringing about a continuous supply.