HYDRAULIC CYLINDER Russian patent published in 1996 - IPC

FIELD: hydraulic drives of press and assembly sets of power tables of building-block machines and other hydraulically- operated machines. SUBSTANCE: hydraulic cylinder has sleeve 1, front cover 2 and rear cover 3, main rod 1 with inner bore 5 and piston 6 mounted in sleeve 1 forming working chambers 7 and 8. Hydraulic cylinder is additionally provided with inner bore 10 on which piston is mounted. Piston 11 is located in cover-sleeve 12 owing to which additional hydraulic cylinder is formed whose return chamber 13 is connected with inner bore 10 by means of check valve 21 built in additional rod 9. Inner bores 5 and 10 of rods 4 and 9 are connected with working chambers 7 and 8 of hydraulic cylinder through radial holes 25 and 26. Section area of inner bore 10 of additional rod 9 exceeds area of section of inner bore 5 of main rod 4. Spool valve 27 loaded with spring 33 is mounted in inner bores 5 and 10 of rods 4 and 9. Spring 33 is mounted in inner bore 10 of additional rod 9. Spool valve 27 has external circular bore 35 embracing radial holes 25 and 26 of both rods 4 and 9. EFFECT: enhanced reliability. 1 dwg