Cutter

Harvesters – Cutting – Cutter members

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Details

56 175, 56DIG17, 56DIG20, A01D 3473

Patent

active

055619720

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to the general field of lawnmovers and other cutting apparatus of the rotary type, with particular application to dual discharge lawn mowers, wherein the grass, leaves and the like can either be cut and discharged via a discharge chute in the blade housing, (referred to herein as catching or scattering"), or alternatively cut into smaller particles and dispersed back onto and into the lawn, (referred to herein as "mulching").


BACKGROUND OF THE INVENTION

Lawnmowers have generally hitherto been designed either to catch lawn clippings in a catcher for disposal, or to recut or mulch clippings and discharge them back into the lawn.
Prior art lawnmower blades, whether disc and flail blades or bar type blades, designed for ejection of the clippings via a discharge chute in the blade housing do not mulch and disperse the clippings satisfactorily back into the cut lawn even when mounted to a lawnmower housing designed for this purpose.
Lawnmower blades designed for mulching and discharge of clippings back into the lawn often fail to operate satisfactorily in wet grass, and also do not satisfactorily perform catching or scattering of clippings, especially if the discharge chute is disposed rearwardly in the blade housing. Various forms of blades have been designed for the purpose of cutting and mulching the grass and dispersing of the clippings back into the lawn, as described in U.S. Pat. Nos. 2,809,488, 3,003,298, 3,382,653, 3,531,923, 4,134,249, 4,292,791) and 4,617,788.
These mulching blades typically produce uplift and/or downdraft, which in conjunction with a suitably shaped blade housing causes a cycling of air and clippings substantially inwards and downwards as the means for dispersing the clippings into the lawn, and do not perform said dispersal satisfactorily when fitted to a lawnmower with restrictions or variations in the height of the blade housing, such as a raised discharge runway.
The prior art includes attempts to achieve dual operations, either discharging clippings into a catcher or alternatively dispersing the same back into the lawn, such as in U.S. Pat. Nos. 3,085,386, 3,132,457 and 3,192,692, which show a mulching assembly with allowance for a discharge opening in the blade housing.
The housing does not include a raised discharge runway to facilitate discharge of the clippings into a catcher, as such a runway would tend to disrupt the aforementioned cyclical airflow and adversely affect the dispersal of the clippings into the lawn when mulching. The discharge opening is positioned on the side, rather than the rear of the blade housing to allow removal of the clippings from within the blade housing as soon as possible.
The catching performance is relatively poor because this type of blade does not produce significant circumferential circulation within the blade housing to effectively eject the clippings out of the blade housing and into a catcher. The inwards and downwards circulation generated by the prior art mulching blades causes a substantial proportion of the grass clippings to be recut before being discharged from the blade housing when catching. This mices moisture and juices from the clippings, which can cause clogging and make emptying the catcher difficult, especially if the grass being cut is wet or lush. An appreciable portion of the clippings also tend to be dispersed into the lawn in the process. The fine mulch does not lend itself to being discharged with sufficient energy to compact well into the catcher.
Furthermore, said prior an bar type blades exhibit a noted tendency towards bending or deforming the engine or blade shaft to which they are attached at times when certain obstructions are encountered, due to the end of the blade being forced downwards as it moves forwards under the obstruction. This is due in pan to the particular configuration of the extreme outer cutting tip.
A further problem encountered with the prior blade mentioned above is the tendency to enwrap certain types of leaves, especially long leaves such as f

REFERENCES:
patent: 2737772 (1956-03-01), Jacobsen
patent: 2809488 (1957-10-01), Sewell
patent: 3085386 (1963-04-01), Slemmons
patent: 3220170 (1965-11-01), Smith et al.
patent: 3382653 (1968-05-01), De Buigne
patent: 3755999 (1973-09-01), Meyer et al.
patent: 4213289 (1980-07-01), Kamppinen
patent: 4318268 (1982-03-01), Szymanis
patent: 5033259 (1991-07-01), Adcock
patent: 5094065 (1992-03-01), Azbell

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