GB371924A - Improvements in and relating to grabs - Google Patents

Abstract

371,924. Grab - buckets. BARNARD, D. J., 8, Strathfield Gardens, Barkirig, Essex. Jan. 27, 1931, Nos. 2652 and 32926. [Class 78 (iv).] In a single-chain grab in which the bucket sections are opened by hand or by dumping, part of the mechanism for closing and locking the bucket sections is mounted on a cross beam on which the bucket sections are pivoted, and part on an arm pivotally mounted on the spreader arms or a member secured thereto. The bucket sections 1, 2, Fig. 1, are pivoted on pins 3, 4, on a cross beam 5 and have spreader arms 6 pivoted by pins 8, 9 onplates 10. The locking mechanism comprises a pair of gravity catches 11 which are pivoted on a shaft 12 on the cross beam 5 and are held engaged with rollers 13 on a pair of arms 14, pivoted on the arms 6, by rollers 20 on links 18 supported at 19 on the arms 14. The rollers 20 are disengaged from the catches 11 by the arm 21 of a lever 21, 22, which may be operated by a cord 23 to open the grab by hand, without dumping. The hauling rope 24 is secured to the grab at 25 and passes round a pair of pulleys 16 carried on the arms 14 so that when the. grab is dumped, the pressure between the catches 11 and the rollers 13 is reduced considerably and the'lever 21, 22 falls due to its own weight and lifts the links 18 from the catches 11 which then fall outwardly. If the. rope 24 is now drawn in to lift the grab, the arms 14 are raised until plates 28 thereon engage plates 29 on the head of the grab. Continued drawing-in raises the grab and the bucket sections 1, 2 fall open. To close the grab, the rope 24 is paid out whereby the arms 14 fall and a pin 30 thereon engages a projection 31 on the catches 11 and rotates them into engagement with the rollers 13, the sections 1, 2 then closing on the rope 24 being drawn in. An arm 32 secured to the end of an arm 34, fixed at one end to the plate 1a and pivoted at the other to a bracket on'the cross beam 5, projects vertically when the sections 1, 2 open so as to raise the arm 22 and hold the arm 21 away from the rollers 20. A guard box 37 on the section 1, for preventing the pulley 16 coming into contact with the material being handled, is provided with a flap 38, which is hinged at 39 and connected by a link 40 to the arm 32 so that it is closed when the sections 1, 2 are open, but opens during the closing movement of the sections . to allow any material that may have dropped in the box to be discharged. In a modification, Fig. 3, the arms 6, carrying the arms 14, are. rigidly connected to the plates 10 and the arms 14 are pivoted on members secured to the arms 6. If, when, the grab has been opened in mid-air by pulling the cord 23, the rope 24 is paid out a weight 53, pivoted at 19 on the arms 14, engages a projection 31 on the catches 11 and rotates them into engagement with the rollers 13. When the arms 14 are now raised by the rope 24, a weight 49, mounted on rollers 59, moves down a track between the arms 14 and, through a link 48, returns the arm 21 under the rollers 20. In a further modification, Fig. 7, the gravity catches 11<x> are mounted on the arms 14 and the rollers 13<x>, engaging therewith, on the cross beam 5. When the grab is opened by hand the lever 22 bears against a pin 62 connected to the weight 49 and, through a link 61, disengages the catches from the rollers 13<x>, If the grab is now dumped, the weight 49 rolls down its track and withdraws the catches. To close the grab the rope 24 is paid out, the arms 14 falling into the position shown in dotted lines and the catches 11<x> engaging the rollers 13<x> so that the sections 1, 2 close when the rope 24 is drawn in.