Patent GB-961296-A (GB)
Title: Hydraulic lifting device
IPC: B65H54/54
Filed: 1959-07-08
Abstract: 961,296. Reels; hydraulic jacks; load handling machines. MASTABAR MINING EQUIPMENT CO. Ltd., E. TEBB, and C. H. PERRY. July 5, 1960 [July 8, 1959], No. 23464/59. Headings B8H, B8J and B8M. [Also in Division D1] An hydraulic lifting device, e.g. for reels or drums, comprises a base 10 and an upright support 16 at one edge thereof, a pair of spaced, parallel, lifting arms 22 pivotally secured to the upper region of the support and extending forwardly over the base and having means at the free ends thereof for supporting a reel to be lifted, and an hydraulic ram 34 connected at one end to the base intermediate the arms and at the other end arranged to support the arms for pivotally raising and lowering the arms relative to the base. There is driving means 76 mounted on one of the lifting arms and connected to the support means on that arm for rotating the support means, the latter and the similar support means on the other lifting arm being adapted to carry between them a core member including means for releasably retaining the end of a length of material to be wound on to the core member, the material constituting the said load, the core member being rotatable by the support means to effect the winding of the material. As shown, an electric motor 70 is connected by a belt 82 to a variable speed gear 76, the output shaft 84 of which drives a hollow splined shaft 86 of a driving dog 88 that releasably receives a core member; the other arm 22 carries an idler dog 90 serving to releasably receive the other end of the core member. Both dogs have two identical, contiguous, parallel slots 92 to receive a core member consisting of two lengths of T-section material provided with lugs through which, and fastener loops on a length of belting to be wound, is passed a hinge pin so that winding of the belting may be started. On completion of the roll of belting the core member halves are collapsed towards one another after removal of the hinge pin and withdrawn from the roll. The dogs 88, 90 are axially displaceable by arms 116 having forks 110 engageable in circumferential grooves 108 formed in the dogs. According to the Provisional Specification rolls &c. of material are lifted from the ground ready for unrolling. The hydraulic ram 34 comprises an outer member 32 providing a working chamber 36 within which slides an inner member 30 having a piston 38, the space behind the piston constituting a reservoir 40 for hydraulic medium. Within the reservoir and mounted on the piston is a two-stage pump 42 operable from externally of the ram 34 and comprising a cylinder 44 secured to the piston 38 and slidably receiving coaxially arranged pump pistons 46, 48, the larger diameter piston 46 being formed with a bore 47 within which reciprocates the piston 48 actuated by a piston rod 50 and crank 52 operable on rotation of a spindle 54; the bore 47 is formed with a shoulder 49 so that when the piston-rod 50 is raised the piston 48 bears on the shoulder to raise the piston 46, and during this time hydraulic medium is admitted to the cylinder 44 through an inlet valve 56. Movement downwards of the piston-rod by rotation of the crank causes the piston 48 to move down the bore 47 until a shoulder 57 on a: clevis 58 bears against a spring 60 and causes the piston 46 to move down the cylinder 44, hydraulic medium then being forced through a passage 62 in the piston 38 past a valve 64 and into the chamber 36, thus causing the ram 34 to expand. As the lifting device takes the weight being lifted the pressure in the chamber 36 rises to support that weight and the pressure in the cylinder 44 and against which the pistons 46, 48 have to act rises to a similar value so that as a result of this increased pressure in the cylinder 44, the piston 46 is urged against the cylinder closure member 43 and thereafter only the piston 48 reciprocating with a reduced stroke is effective to pump hydraulic medium from the reservoir 40 to the cylinder 44 and chamber 36. To lower the weight-supporting arms of the lifting device, the piston-rod 50 is moved downwardly until the shoulder 57 abuts the spring 60 which is compressed and allows the shoulder to depress a striker member 66 and open an exhaust valve 68, hydraulic medium being then allowed to flow freely through the piston 46 and enabling continued downward movement of the piston-rod to move both pistons to the bottom of the cylinder 44 where the piston depresses a striker member in the piston 38 to open a valve 64 which accordingly allows hydraulic medium to return from the chamber 36 to the reservoir 40.