Harvesters – Cutting – Rotating cutting-reel type
Patent
1992-07-28
1993-11-30
Bagnell, David J.
Harvesters
Cutting
Rotating cutting-reel type
56 167, A01D 3442, A01D 3456
Patent
active
052654044
DESCRIPTION:
BRIEF SUMMARY
This invention relates to grass cutting units of the type having a driven cutter reel cooperating with a stationary bottom blade and is more particularly, though not exclusively, concerned with such cutting units adapted to be mounted in groups of three or more on self-propelled or trailed grass cutting machines.
The conventional grass cutting unit comprises parallel side plates secured at opposite ends of a bottom block which provides the stationary bottom blade. The cutter reel has helical blades disposed about a reel shaft and the ends of this shaft project through apertures in the side plates for engagement with suitable bearings.
It is on occasion necessary to remove a cutter reel for maintenance or repair. Hitherto, this has often meant the removal of at least one side plate and this is a time consuming operation. Moreover, the re-assembly procedure will usually require tightening of bolts in a specified order and to specified torque levels, if undesirable stresses in the assembled unit are to be avoided. Whilst the assembly procedure can be accurately controlled at the time of manufacture, there is a risk that the correct procedures will not be followed during maintenance or repair work carried out in the field.
To avoid the necessity of removing one or more side plates, it has previously been proposed to form open ended slots in the side plates with the reel shaft being withdrawn through the slots. It is a problem, however, that the existence of open ended slots may significantly reduce the rigidity of the side plates, this rigidity being important in holding the reel and bottom blade in the correct cutting relationship.
It is one object of this invention to provide an improved grass cutting unit in which the correct positional relationship between the cutter reel and the bottom blade is accurately maintained and in which the cutter reel can be removed--for maintenance or repair purposes--without disassembly of the side plates.
Accordingly, the present invention consists in one aspect in a grass cutting unit comprising a transversely extending bottom block providing a bottom blade; a pair of generally parallel side plates secured to the bottom block at respective opposite ends thereof; a pair of bearing supports provided one on each side plate and each comprising a support bearing element, at least one of the bearing supports being removably secured to the associated side plate and having the bearing element thereof projecting inwardly of the side plate; and a cutter reel having a reel shaft and a plurality of blades rigidly disposed thereabout for cutting engagement with the bottom blade, wherein the reel shaft is provided at its ends with shaft bearing elements engaged respectively with the support bearing elements so as rotatably to support the cutter reel between the side plates, characterised in that the length of the reel shaft is less than the transverse separation of the side plates such that upon removal of said at least one bearing support, the cutter reel may be withdrawn from the side plates in a direction normal to the shaft length.
Advantageously, both bearing supports are removably secured to the associated side plate and have the bearing element thereof projecting inwardly through an aperture in that side plate.
Preferably, each support bearing element comprises a bearing collar and each shaft bearing element comprises a shaft portion extending within the respective bearing collar.
Suitably, a taper roller bearing is provided between each bearing collar and the corresponding shaft portion.
The use of taper roller bearings is generally preferred for the mounting of cutter reels since they can be adjusted to eliminate radial clearance and have, for a comparable size, a longer life than most other bearing types. A disadvantage of taper roller bearings in this application is that the relative positions of the coned faces within the bearing must be accurately maintained if the correct relationship is to be assured between the cutter reel blades and the stationary bottom blade. It has bee
Aldred Edward J.
Mills John
Bagnell David J.
Ransomes Sims & Jefferies Limited
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