Implements or apparatus for applying pushing or pulling force – Portable implements or apparatus for tensioning flexible... – Including expansible chamber fluid motor drive
Reexamination Certificate
1999-06-03
2001-09-04
Marcelo, Emmanuel M. (Department: 3653)
Implements or apparatus for applying pushing or pulling force
Portable implements or apparatus for tensioning flexible...
Including expansible chamber fluid motor drive
Reexamination Certificate
active
06283451
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to hydraulic cable tensioners, more particularly, to a portable, lightweight hydraulic cable tensioning device for use in tensioning mine roof cable bolts and cable trusses.
2. Prior Art
Hydraulic cable tensioners have been used to apply tension to a length of installed cable having one fixed end such as a conventional cable bolt having a barrel and wedge assembly or a cable truss having a length of cable terminating with a barrel and wedge assembly. Tension is applied to the installed cable between the barrel and wedge assembly and the fixed end of the cable by pulling on the free end of the cable while urging the barrel and wedge assembly towards the fixed end of the cable.
FIG. 1
depicts a conventional cable tensioning unit U formed of three separate steel cylinders, two being hydraulic cylinders HC coupled together via a yoke Y and a central cylinder CC which receives the cable to be tensioned. Hydraulic fluid is fed to the hydraulic cylinders HC via hydraulic lines L and manifolds M from a remote hydraulic fluid supply unit located at a mining machine. The steel unit U is heavy, typically weighing about eighty pounds, and must be held in one place by one operator at the location of the cable bolt or cable truss to be tensioned while a second operator located at the mining machine operates the controls for the hydraulic fluid delivered to the unit U.
The maximum hydraulic pressure applicable to the unit U is about 2,500 psi resulting in tensioning of an installed cable by about eight tons. This conventional cable tensioner is cumbersome due to its weight and need for two people to install and operate the unit.
Accordingly, a need remains for a hydraulic cable tensioning device which may be readily portable and held overhead by one individual as well as operated at the location of the cable bolt or cable truss to be tensioned.
SUMMARY OF THE INVENTION
This need is met by the hydraulic cable tensioning device of the present invention which is used to induce tension in a cable, the cable having one end fixed to a structure and a free end bearing an attachment assembly. The device includes (1) a unitary body defining a cable receiving bore and an elongated cavity, (2) a cable gripping member received within the cable receiving bore, (3) an elongated member received within the cavity and having a first end extending out of the body, (4) a piston slidably fitted within the cavity and fixed to a second end of the elongated member, thereby defining a first chamber on one side of the piston and a second chamber on an opposite side of the piston and (5) a yoke attached to the first end of the elongated member, the yoke defining a bore aligned with the cable receiving bore and having an abutment surface. The body is preferably formed from aluminum.
When a cable having one end fixed to a structure and a free end bearing an attachment assembly is received in the bore and the piston is urged towards the yoke, the cable gripping member grips the cable while the elongated member moves out of the cavity thereby urging the abutment surface against the attachment assembly and tensioning the cable between the attachment assembly and the fixed end of the cable. Preferably, the body defines a pair of elongated cavities positioned on opposite sides of the bore, each cavity receiving an elongated member with a piston slidably fitted within the cavity and fixed to one end of the elongated member, thereby defining a first chamber on one side of each piston and a second chamber on an opposite side of each piston, with the yoke being fixed to the elongated members. The piston is moveable towards the yoke when pressure within the first chambers is greater than pressure within the second chambers. The pressure in said first chambers is up to about 5,000 psi. The device further includes a pair of hydraulic fluid supply lines and the body further defines (i) a first passageway in fluid communication with one hydraulic fluid supply line and the first chambers and (ii) a second passageway in fluid communication with the other hydraulic fluid supply line and the second chambers.
REFERENCES:
patent: 3907338 (1975-09-01), Hayes, Jr. et al.
patent: 4615509 (1986-10-01), Biass
patent: 4641816 (1987-02-01), Kishida et al.
patent: 5277406 (1994-01-01), Knight
patent: 1800025 (1968-10-01), None
“Mincon Cable Tensioning Jack, Model MTJ-35”, BLM Mincon Inc. Mining and Construction Products, 2pp.
“Spring Loaded Ram Model PTJ5s”, Florida Wire and Cable Company, 2 pp.
Stankus John C.
Taylor Kendal L.
Jennmar Corporation
Marcelo Emmanuel M.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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