Jackhammer

Abstract: Jackhammer manufacturers have recently developed lightweight (45-60 lbs) jackhammers intended to reduce the required lifting and pushing forces during operation However, the vibration characteristics of the lightweight jackhammers and their effect on muscle activity are currently unknown The objective of this study was to compare the measured vibration and muscle activity between: (i) conventional (90 lb) and light weight (60 lb) jackhammers, (ii) different pavement type/thickness combinations, and (iii) pneumatic and hydraulic jackhammers Five jackhammers were tested on 4 and 6 inch thick asphalt and concrete pavements by four experienced operators Analysis of the results revealed that both weight classes averaged 97 m/s(2) at the 20 Hz weighted 1/3 octave band frequency, and the TLV of daily exposure for either weight class of jackhammer was less than 15 hours/per day There was an approximately 33% difference in vibration measured on the hand of the operators due to pavement thickness, 30% due pavement type, and no difference due to power source Conventional jackhammers overall produced higher muscle activity than lightweight jackhammers Although selection of the correct jackhammer for the job involves many factors including pavement type and thickness, the results of this research can be used to assist in selecting the appropriate jackhammer

Abstract: Disclosed herein is a hydraulic hitting type jackhammer with an auto lubricant feeder and a pneumatic pressure supply, in which the piston is lifted by the hydraulic pressure, strikes the chisel formed at the lower portion by the power of the compressed gas to thereby break the objects to be broken, the lubricant feeder to supply the lubricant automatically from the upper portion to the supporting portion is formed in order to minimize the abrasion by friction of the supporting portions supporting the chisel which is struck by the high speed and pressure dropping, thereby maximizing the lifespan of the jackhammer.

Abstract: A hand-operated power tool ( 10 ), in particular a drill hammer and/or jackhammer, has a housing which has a drive mechanism for driving a tool ( 12 ) that is receivable in a tool receptacle ( 13 ) and, in the rear region ( 14 ), remote from the tool receptacle ( 13 ), has a handle assembly ( 20 ) for grasping and handling that engages the housing ( 11 ). The handle assembly ( 20 ) is vibration-damped with respect to the housing ( 11 ), with the components contained in it, at least and substantially in the axial direction, by means of a vibration-damping device.

Abstract: Jack hammer with a socket for the axially limited tool which is loaded from above by a hammer when this is released and urged forward by a hammer spring after the motor powered cocking movement so that the hammer either strikes the tool rebounding from the face, or else completed a series of damper controlled idle strokes. A pneumatic damping arrangement is provided for the idle strokes of the hammer. The damping facility should consist of a compression chamber at the rear end of the drill spindle accommodating the tool so that a compression piston on the end of the hammer can ride into the chamber in the idle movement, the system completed by a choke channel for compression air escaping from the compression chamber. The chamber should be annular and cylindrical in design, limited outside by the expanded end of the spindle bore and inside by the hammer tip with the adjoining pin acting as compression piston.