GB2137063A

GB2137063A - Cylinder Lawnmowers

Info

Publication number: GB2137063A
Application number: GB08408120A
Authority: GB
Inventors: John F Robinson; Berjinder S Sehmbi; Brian P Onufryk; John H Upton; Richard A Shawe-Taylor
Original assignee: BIRMID QUALCAST
Current assignee: BIRMID QUALCAST
Priority date: 1983-03-30
Filing date: 1984-03-29
Publication date: 1984-10-03
Also published as: GB8408120D0

Abstract

A cylinder lawnmower comprises a cutting cylinder (10) mounted for rotation relative to a fixed bottom blade (12). An adjustment mechanism (13) is provided for adjusting the location of the bottom blade (12) relative to the cutting cylinder (10). The adjustment mechanism (13) is releasably engaged with the bottom blade assembly (12, 15) in such a manner that removal and replacement of a bottom blade is achieved without disturbing the adjustment setting. The blade assembly may be removed by depressing plunger 26 against spring 27 until projection 28 is clear of the top edge of the arm 15. The arm can then be moved laterally off the pivot pin 25 (Fig. 3). <IMAGE>

Description

SPECIFICATION Cylinder Lawnmowers The clearance gap between the fixed bottom blade and the rotating cutting cylinder of a lawnmower is normally set to within fine tolerances by the original manufacturer. The gap may require adjustment from time to time during use of the mower and it is therefore desirable to provide a simple manual adjustment mechanism.

One such mechanism is shown in our U.K.

Patent 1 314377. In this mechanism the bottom blade is attached to a cross frame member by means of leaf springs, and adjustment of the blade relative to the cutting cylinder is achieved by raising or lowering mounting brackets secured to the opposed ends of the blade, each bracket having an associated T-bolt extending through a side frame member and bearing a compression spring. Rotation of a nut engaged with each bolt produces adjustment of the bottom blade in relation to the cutting cylinder.

Although in the above mechanism it is relatively easy to detach the bottom blade from the mower for repair or replacement, it would clearly be an advantage if this could be done without having to dismantle and reassemble the adjustment mechanism.

In accordance with the present invention there is provided a cylinder lawnmower comprising a cutting cylinder mounted for rotation relative to a fixed bottom blade assembly, an adjustment mechanism for adjusting the location of the bottom blade assembly with respect to the cylinder, and means releasably engaging the bottom blade assembly with the adjustment mechanism in such a manner that disengagement of the assembly is achieved without disturbing the adjustment setting.

In a preferred embodiment of the invention the releasable engaging means includes a resiliently biased retaining member, the retaining member being movable against its resilient bias independently of the adjustment mechanism.

Recessed mounting means preferably accommodate pivotal movement of the blade toward and away from the cutting cylinder against a resilient bias when the blade assembly is engaged with the adjustment mechanism.

Further pivotal movement of the blade away from the cutting cylinder is then permitted only when the blade assembly is disengaged from the adjustment mechanism, the further pivotal movement enabling removal of the blade from its recessed mounting. The blade assembly may, for example, include opposed lateral projections pivotally supporting the assembly in respective recessed mounting members, each projection being movable into and out of its respective recess only when the assembly is disengaged from the adjustment mechanism.

The blade assembly preferably includes at least one adjustment arm projecting forwardly beyond the cutting edge of the blade, the or each arm being pivotally connected to the adjustment mechanism. The assembly is then disengaged from the adjustment mechanism by lateral movement of the or each adjustment arm relative to the respective pivot, this movement normally being prevented by the resiliently biased retaining member.

By way of example only, an embodiment of the invention is illustrated in the accompanying drawings, in which: Fig. 1 is a side elevational view of a bottom blade mounting assembly in a cylinder lawnmower; Fig. 2 is a section on line 2-2 of Fig. 1; Fig. 3 is a detail of Fig. 2 showing the plunger depressed to release the blade assembly from the adjustment mechanism; and Fig. 4 is a view in the direction of arrow "A" in Fig. 1.

Referring to these Figures, a cylinder lawnmower includes a cutting cylinder 10 (shown in outline only) mounted between opposed side walls 11 of a mower housing, only one side wall 11 being shown in the drawing.

The cylinder includes a central shaft 35 rotatably mounted in opposed bearings 34 carried by respective bearing support housings 33 secured to the respective side walls 11.

The rotating cylinder 10 cooperates with a fixed bottom blade 12 to perform a cutting action in a well known manner. An adjustment mechanism 1 3 is provided to adjust the clearance gap between the cutting edge 14 of the bottom blade 1 2 and the cutting cylinder.

A pair of adjustment arms 1 5 are riveted to the opposite ends of the bottom blade, each arm 1 5 being pivotally connected to a respective adjustment mechanism 13. The drawing illustrates the arm 1 5 and the adjustment mechanism 13 at one end of the blade 12 but it will be appreciated that an identical arrangement is provided at the opposite end of the blade.

The adjustment mechanism 1 3 includes a rod 1 6 in screw threaded engagement with a Tshaped nut 17, the shank of the nut passing through a hole 20 in an end portion 21 of a forward extension arm 33b of the support housing 33, the head 19 of the nut being resiliently retained against the underneath surface of the support by a pre-tensioning spring 22 retained on the nut by a pin 23.

At the other end of the rod 16, an integrally formed rectangular plate 24 carries a pin 25 about which the arm 1 5 is able to pivot, the plate 24 being slidably received in a plunger 26 which is normally urged to the position shown in Figs. 1 and 2 by a chatter spring 27. In this position the arm 15 is retained against plate 24 by downwardly projecting portion 28 of the plunger 26.

To adjust the location of the bottom blade 12 with respect to the cutting cylinder the T-nut 1 7 is rotated to raise or lower the pivot pin 25 on which arm 1 5 is mounted. The pivot pin 25 may also move temporarily downwards against the bias of spring 22 to accommodate the passage of stones or other hard objects between the bottom blade 12 and the cutting cylinder 10.

Should it be desired to remove the bottom blade 12, this is done by depressing the plunger 26 against the chatter spring 27 until the projection 28 is clear of the top edge of the arm 1 5. The arm can then be moved laterally off the pivot pin 25 as best shown in Fig. 3.

The blade 12 consists of a flat rectangular plate formed into a shallow V-shape. The two rear corners of the plate each include a lateral rectangular ear 29 with a rearwardly curled base 30, the ear being located in a generally triangular recess 31 formed in a rear extension arm 33c of the bearing support housing 33.

One side wall 36 of recess 31 is partly cut away so that, when arm 1 5 is released from pivot pin 25 and the blade assembly is swung downwards, the curled base 30 of the ear 29 pivots to a position in which the ear is aligned with the opening in the wall 36. The blade assembly then drops out of its mounting.

It can be seen therefore that the removal of the entire bottom blade assembly is achieved in a simple manner and without disturbing the adjustment mechanism. Accordingly, when the blade is replaced, or a replacement blade is fitted, this can be done without the need to readjust the clearance gap between the blade and the cutting cylinder.

Claims

1. A cylinder lawnmower comprising a cutting cylinder mounted for rotation relative to a fixed bottom blade assembly, an adjustment mechanism for adjusting the location of the bottom blade assembly with respect to the cylinder, and means for releasably engaging the bottom blade assembly with the adjustment mechanism in such a manner that removal and replacement of the bottom blade is achieved without disturbing the adjustment setting.

2. A lawnmower according to Claim 1 in which resiliently biased retaining means retain the assembly in engagement with the adjusting mechanism, the retaining means being movable against its resilient bias independently of the adjustment mechanism to permit disengagement of the blade assembly from the adjustment mechanism.

3. A lawnmower according to Claim 1 or Claim 2 further comprising recessed mounting means accommodating limited pivotal movement of the blade toward and away from the cutting cylinder against a resilient bias when the blade assembly is engaged with the adjustment mechanism.

4. A lawnmower according to Claim 3 in which further pivotal movement of the blade away from the cutting cylinder is permitted when the blade assembly is disengaged from the adjustment mechanism, the further pivotal movement enabling removal of the blade from its recessed mounting.

5. A lawnmower according to Claim 2 in which the blade assembly includes a pair of mounting brackets secured to opposed ends of the blade, the brackets projecting forwardly beyond the cutting edge of the blade and each bracket being laterally retained on a pivot of the adjustment mechanism by the retaining means.

6. A lawnmower according to Claim 5 in which the adjustment mechanism includes manually operable means for raising or lowering the pivot to adjust the location of the bottom blade assembly.

7. A lawnmower according to Claim 6 in which the pivot is further movable against a resilient bias to accommodate movement of the bottom blade assembly away from the cutting cylinder during mowing.

8. A lawnmower substantially as herein described with reference to the accompanying drawings.