color="#CC0000">Gentle
Jack
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You Get
Jackhammer Video play now or Right Click to Download One of the key differences is that this tool utilizes heat and doesn't exhaust it with a loud bang. The air input temperature in the "Gentle Jack's" system is 210 degrees Fahrenheit, while standard equipment uses a cool 80 degrees. When air is compressed, it heats up. Conventional compressors and breakers throw away most of this heat energy and compression energy contained in the air to drive the breaker. The exhaust air is at ambient temperature and atmospheric pressure. This eliminates freeze up and exhaust noise. The problems of exhaust freeze, exhaust fog and excess dust cannot occur with the Gentle Jack equipment. The Vibration less operation is based on two key points. There is a constant air pressure between the piston hammer and the housing throughout the stroke cycle, powering the down stroke of the piston but resulting in no variable forces being imparted to the tool or the operator. The system then allows a variable air pressure, powering the upstroke of the piston which works simultaneously on equal areas of the lower face of the piston and the upper face of the breaker point. Because of the equal areas, the forces are confined to the hammer being urged in an upward direction thus preparing for another down stroke and the breaker point being urged downward against the rock or concrete. This concept utilizes all of the compression forces and compression heat invested in the equipment. A spring-loaded valve and radial ports on a central air tube control air movement through a pneumatic concrete breaker. The tool's hammer is isolated from its housing and rides on a column of hot expanding air. As a result, the unit is nearly Vibration-less. Traditionally, jackhammers have employed a reciprocating, pneumatically-driven piston, striking many blows each minute, to break concrete. This new design employs fewer but heavier blows to accomplish the same function. In conventional jackhammers, the 4 to 5-lb. hammer usually has a stroke of 2 to 3 inches and requires a 25-hp compressor and H.R.H. to provide input air at about 80F. The Vibration less jackhammer employs a 17-lb. hammer moving through a stroke of 11 inches. The breaker point also weighs about 17 lbs. The design requires hot (250F) input air, which is allowed to expand adiabatically against the hammer. After the hammer has been lifted into position for a stroke, it's driven down by 50-psi input air. Input air pressure is held constant at all times. The hammer is not mechanically linked to the casing of the tool and the air is exhausted for atmospheric pressure. So there's very little vibration transmitted up the tool to the operator. In fact, one can balance a quarter atop the unit while it's breaking concrete. Pressurized air introduced to the tool from the compressor through an insulated line exerts force against the external shoulder of hammer and internal shoulder of the housing, forcing the hammer against the breaker point. The point is caught by a retainer hook. When the operator applies 30-lb. downward force, the shoulder on the breaker point is stopped by rubber bumper rings. Radial ports and internal annulus on the hammer are then in register with the upper cross port in the central air tube, permitting pressurized air to flow down the center tube to depress the valve piston against a spring until it hits stop.
GENTLE JACK Specification Chart Model VHB-80 Breaking Rate: The Gentle Jack will hold its own against a McDonald 60 lb. hammer and will do 90% of what an 80 lb. will do but without the wear and tear on the operator or the equipment.
Makes half the audible noise of a conventional hammer
Energy Feedback to operator: 3 ft. lb./min. -
Conventional hammers are more like 1500 foot-lbs./min.
Next, air flows into the space between the rear face of the breaker point and the lower hammer face. As air expands, it raises the hammer, the internal hammer annulus passes the upper port in center tube, cutting off air flow through this passage. The hammer operated by expansion of hot input air. Standard, heavy-duty concrete breakers deliver 87 ft-lb. impact with 75 to 100 psig input air. Our breaker produces 135 ft-lb. impact with 50 psig air, 194 ft-lb. with 75-psig air. Expanding air under the hammer raises it to near top position in housing. Air pressure beneath the hammer drops from 50 to 0 psig and air temperature drops from 250 to 90F as air expands adiabatically. As hammer rises, pressurized air outside the hammer, but inside the housing, is forced into the air supply line. This air movement ensures constant down force on the hammer throughout the stroke cycle and constant up force on the cylinder housing. Lower control valve's piston begins rising as pressure on it decreases. After the hammer reaches top of stroke, 50-psig air acts on the hammer shoulder to start it moving down toward breaker point. The control valve's piston reaches its top position. As the hammer descends, air below the hammer is forced past the valve piston's stem and out through ports in the breaker point shoulder to atmosphere. Because exhaust is at atmospheric pressure, there's no detonation or exhaust noise. |
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Gentle Jack is temporarily un-available awaiting manufacturer