The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 05, 1997
Filed:
Jun. 15, 1995
Bretec Oy, Lahti, FI;
Abstract
The invention relates to a hydraulic percussion hammer comprising a piston (1), a pressure accumulator (7) in the high pressure circuit, a main valve (8) alternately conducing a high and low pressure to at least one of the pressure surfaces (2,4) of the piston (1) for making the piston (1) move reciprocally, and a tool (3) which the piston (1) strikes, and, for the purpose of controlling the main valve (8), a control pressure valve (9) which opens when the pressure exceeds a set value. According to the invention, the control pressure valve (9) is placed in such a way that the spindle (27) of the control pressure valve (9) is connected from one end to the high pressure circuit of the hydraulic percussion hammer. Furthermore, for the purpose of adjusting the maximum and minimum operating pressure of the hydraulic percussion hammer the other end of the spindle (27) of the control pressure valve (9) comprises a control space (29) connected through the hydraulic ducts to at least two pressure control devices (30,31,32,33) connected hydraulically in parallel or in series.