Rearwardly, the head has a second part having expansion holders with teeth to dig out the perimeter of the holes thereby cutting clearance for the casing. The forward portion has conventional earth boring teeth which dig out the largest area of the hole being bored. More particularly, the invention relates to a head which has essentially two parts - one displaced approximately 90° relative to the axis of rotation of the head from the other. This invention relates to a new and improved head for horizontal earth boring. A boring head according to claim 3 in which one said abutment is adjustable in position to adjust the size of said outside diameter. An earth auger head according to claim 1 which further comprises a first abutment on each said second arm and a second abutment on each said expansion holder, said abutments coming into contact with each other to limit outward pivotal movement of said holder as said head is turned about its axis of rotation in first direction to limit the outside diameter of the hole being bored.Ĥ. A boring head according to claim 1 in which one said spacer is located adjacent the outer end of said second arm and is formed with an abutment and each said holder has a set screw engaging said abutment to limit the outward extension of the second tooth held in said holder.ģ. An earth auger head having an axis of rotation comprising a shaft, a plurality of first arms each carrying a plurality of first tooth holders, first teeth in said first tooth holders, said first teeth positioned to bore earth at the end of a hole substantially transverse to said axis of rotation, a plurality of second arms spaced rearwardly of said first arms and disposed substantially midway between said first arms, said second arms comprising diametrically disposed, parallel, thin, narrow front and rear expansion arms, each said expansion arm transverse to said axis and spaced relative to each other along said axis, said first and second arms fixed to said shaft, an expansion holder mounting means on the outer end of each said second arm disposed between said front and rear expansion arms, a pair of spacers between said front and rear expansion arms spacing said expansion arms apart, an expansion holder pivotally mounted in each said mounting means about a second axis parallel to said axis of rotation, a second tooth in each said expansion holder pivoting about said second axis between a retracted position inside the perimeter of the hole bored by said first teeth and an extended position outside said perimeter, said second teeth positioned to dig the outside of said hole when in extended position, said second teeth when in extended position being substantially midway between the two adjacent outermost first teeth when viewed in a direction parallel to said axis of rotation, said expansion holders pivoting to extended position when said head is rotated in one direction of rotation and to retracted position in reverse direction of rotation of said head.Ģ. Neil Gardner on Bam Nuttall begins £34.7M cliff resilience project to protect Dawlish coastal railway: ‘I notice that neither the Network Rail or Bam persons felt a.1.Jeffrey Smith on Future of Floods | Low carbon concrete mixes tested in permanent works for Hexham flood defence scheme: ‘I am all for trials to lower the amount of carbon dioxide in.Jeffrey Smith on Long-running campaign to reinstate abandoned railway line in Lake District gathers pace: ‘I am all for this but £90M does not sound like enough to me.on Cracked viaduct on Netherlands high speed rail sees speed restriction extended for two years: ‘I find it hard to believe the 800mm horizontal movement ment.on Technology is key to modernising 19th century water infrastructure: ‘It seems to me that the proposals discussed deal primarily w.John Porter on DfT mulls stripping HS2’s Euston terminus to seven platforms: ‘Seven to nine platforms as a 20 year solution could work if.James Walley on Construction start in sight for £2.4bn ‘invisible energy highway’ between UK and Germany: ‘Literally the object of the project is to increase energy se.on Thanet Parkway becomes newest station on South Eastern rail network: ‘Prisoner Cell Block H? Is that the best that could be done?.
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