GB1434210A - Mast assemblies for material handling vehicles - Google Patents

Abstract

1434210 Masts RAYMOND CORP 25 Sept 1973 [2 Jan 1973] 44815/73 Heading B8H The mast assembly of a material handling vehicle comprises upper and lower mast sections 14, 18, a lifting carriage 17 being movable along the mast section 14 and upon which is located a laterally movable load platform (not shown) which is movable to either side of the mast assembly, the assembly being such that lateral bending moments which are set up on extension of the load platform to either side of the mast assembly are significantly reduced as compared with those set up in a prior-art type device. The lifting carriage 17 is provided with four rollers which run along the mast members 14a, 14b of the mast section 14, the latter in turn being guided on the lower mast section 18 by means of rollers 19a-19d, and a cable 28 extends from an attachment point 29 on the member 18a of mast section 18 over pulleys 21, 23 on mast section 14 to an attachment point 17h on the carriage 17, while a second cable 25 extends from mast member 18b of mast section 18 over pulleys 24, 22 on mast section 14 to an attachment point 17g on the carriage 17 while a ram 10, 11 is connected to a bracket on the mast section 14 for raising and lowering the said section 14 and thus the raising and lowering of the carriage 17. When a load W L is moved through a distance X a moment of magnitude W L X is applied to the carriage 17 and the rollers between the carriage 17 and the mast section 14 apply a clockwise bending moment to the mast section 14 which is resisted by an equal moment of magnitude RL, and the mast section 14 in turn applies a clockwise bending moment to the lower mast section 18 which will be opposed by a moment Py equal to the moment W L X, P and R being the respective roller forces. It is stated that due to the cable arrangements described the moments RL and Py are considerably reduced as compared to those generated in a prior-art type device. In Fig. 5a (not shown), the moments Rh and Py are plotted against the carriage displacement distance both for a prior-art type mast and for the mast described above. In a modification, Fig. 6 (not shown), the lower mast section (18) is itself movably guided in guide members (32a, 32b), while in Fig. 6c (not shown), a three section mast employs two serially-acting rams, while in Fig. 7 (not shown), the outer mast (14a, 14b) of the assembly shown therein is disposed outside the mast (18), and in Fig. 8 (not shown), the cables include slanting sources, but in all the modified arrangements of mast assemblies described the cable arrangements are the same as those described in relation to Fig. 2 above.