GB1183697A

GB1183697A - Telescopic Boom with Proportioned Travel.

Info

Publication number: GB1183697A
Application number: GB163269A
Authority: GB
Original assignee: Baldwin Lima Hamilton Corp
Current assignee: Baldwin Lima Hamilton Corp
Priority date: 1968-01-10
Filing date: 1969-01-10
Publication date: 1970-03-11
Also published as: DE1900820A1; FR2000112A1; NL6900328A; BE726539A

Abstract

1,183,697. Cranes. BALDWIN-LIMAHAMILTON CORP. 10 Jan., 1969 [10 Jan., 1968], No. 1632/69. Heading B8B. [Also in Divisions F1 and F2] A boom assembly, Fig. 1, comprises a shipper 11, normally mounted for swinging and elevating movement on a crane supporting vehicle, a boom 12 movable longitudinally within the shipper 11; a first boom extension 13 slidaby mounted in the boom 12 and a second boom extension 14 similarly mounted within the first boom extension 13. A first double-acting hydraulic actuator 21 interconnects the shipper 11 and the boom 12, and second and third double-acting hydraulic actuators 22, 23 respectively interconnect the boom 12 and the first boom extension 13 and the first boom extension 13 and the second boom extension 14. Flow divider valves 41, 42, Fig. 2, are interposed between the actuators 21 to 23 for establishing fixed proportion simultaneous flow rates of hydraulic fluid to and from all the actuators so that all the extendible members of the boom assembly reach their fully extended and fully retracted positions simultaneously. Fig. 4 shows the valve 42 dividing fluid from line 43 between the actuators 22, 23 for extending movement of the boom assembly. Fluid under pressure enters passage 61, passes to the centres of spools 71, 72 through rate determining ports 78, 79 and out through throttling ports 81, 68 and 82, 69 to passages 62, 63 and lines 44, 45. If, for example the flow through passage 63 becomes less than the predeterrnined rate, the pressure drop across the ports 79 drops, increasing the pressure within the spool 72 and moving it to the left which urges spool 71 to the left by compressing spring 77. This partially closes the throttling ports 81, 68 and restores the previous proportion of hydraulic fluid flow in the passages 62, 63. The valve 41, Fig. 3 (not shown), is constructed similarly to the valve 42 and is illustrated showing the positions of the parts of the valve when the boom assembly is being contracted.