GB2248165A - Cylinder lawnmowers - Google Patents

Cylinder lawnmowers Download PDF

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Publication number
GB2248165A
GB2248165A GB9119978A GB9119978A GB2248165A GB 2248165 A GB2248165 A GB 2248165A GB 9119978 A GB9119978 A GB 9119978A GB 9119978 A GB9119978 A GB 9119978A GB 2248165 A GB2248165 A GB 2248165A
Authority
GB
United Kingdom
Prior art keywords
cylinder
blade
bottom blade
blades
range
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9119978A
Other versions
GB2248165B (en
GB9119978D0 (en
Inventor
Paul Ducker
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ATCO QUALCAST Ltd
Original Assignee
ATCO QUALCAST Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ATCO QUALCAST Ltd filed Critical ATCO QUALCAST Ltd
Publication of GB9119978D0 publication Critical patent/GB9119978D0/en
Publication of GB2248165A publication Critical patent/GB2248165A/en
Application granted granted Critical
Publication of GB2248165B publication Critical patent/GB2248165B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
    • A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
    • A01D34/42—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters having cutters rotating about a horizontal axis, e.g. cutting-cylinders
    • A01D34/62—Other details
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D2101/00—Lawn-mowers

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Harvester Elements (AREA)

Abstract

A cylinder or reel lawnmower comprises a rotatable spiral-bladed cutting cylinder cooperating with a static bottom blade to perform a shear cutting action, the bottom blade having a surface hardness value at least 2.5 times greater than that of the cylinder blade or blades in the area of blade contact.

Description

CYLINDER LAWNMOWERS A cylinder or reel lawnmower for cutting grass and other vegetation generally includes a rotating spiral-bladed cutting cylinder co-operating with a static bottom blade1 the interface between the cylinder and the bottom blade being sufficiently close to perform a shear cutting action.
The materials for the cylinder and bottom blade are generally chosen to provide a cutting system with relatively low wear, while resisting blade distortion if stones or other debris become trapped between the cylinder and bottom blades. The surface hardness of the blades, as measured on the 'wickers' scale, are typically tn the range of 180-240 Hv, with the surface of the cylinder blade being between 0.8 and 1.5 times harder than the surface of the bottom blade.
In practice this hardness relataonship means the bottom blade wears at a greater rate than the cylinder blades, especially when a large number of cylinder blades are present, since the surface of the bottom blade is abraded several times in each cylinder revolution whilst each cylinder blade is abraded only once. As a consequence, the contact area of the bottom blade with the cylinder progressively increases over time as a land is worn on the bottom blade. This leads to an increase in the energy required to rotate the cylinder, either due to the increased area of abrasive contact, or due to the grass being between the blades for a greater time during cutting.
In practical terms, the energy increase 7s generally caused by a combination of these two factors.
It is generally considered that the sharpness of the cylinder blade is more significant than that of the bottom blade when determining cut grass quality and energy consumption. In the above-described cutting system, some self-sharpening of the cylinder blades occurs due to the shear cutting action, but this progressively decreases as the bottom blade wears.
Moreover, when a stone becomes trapped between the bottom blade and a cylinder blade, the impact tends to produce a local expansion of the cylinder diameter which wears a corresponding indentation into the bottom b blade This produces a gap when the other cylinder blades pass the indented area, often causing grass to be trapped at this point and thereby increasing the amount of energy required to maintain cylinder rotation by a factor of up to 4 times.
According to the present Invention the bottom blade of a cylinder or reel lawnmower has a surface hardness value at least 2.5 times greater than that of the cylinder blade or blades in the area of blade contact.
The greater surface hardness of the bottom blade is preferably achieved by hardening the surface of a base metal.
We have found that the resulting cutting system produces less wear of the bottom blade, sharper cylinder blades, and significantly less energy consumption over the life of the lawnmower.
In a particular embodiment of the invention, each metal blade of a multi-bladed cutting cylinder has a surface hardness in the range of 120-200 Hv. The fixed bottom blade comprises a base metal, such as steel, with a hardness in the range 100-180 Hv. On to this base metal is fused a hardened layer comprising, for example, a tungsten carbrde/cobalt mixture. Fusion is achieved by the process of metal spraying under high pressure and temperature.
This produces a bottom blade having an extremely high surface hardness of around 780-850 Hv in the area of blade contact1 and provides a hardness ratio between the surface of the bottom blade and the surfaces of the cylinder blades in the region of 800/200 = 4.

Claims (6)

1. A cylinder or reel lawnmower comprising a rotatable spiral-bladed cutting cylinder co-operating with a static bottom blade to perform a shear cutting action, the bottom blade having a surface hardness value at least 2.5 times greater than that of the cylinder blade or blades in the area of blade contact.
2. A lawnmower according to claim 1 wherein the bottom blade comprises a base metal with a hardened surface layer.
3. A lawnmower according to claim 2 wherein the hardness of the base metal is in the range of 100-180 Hv as measured on the Wickers scale, and the hardness of the surface layer is in the range of 780-850 Hv.
4. A lawnmower according to claim 1 or claim 2 wherein the surface hardness of the cylinder blade or blades is in the range of 120-200 Hv as measured on the Vickers scale, and the surface hardness of the bottom blade is in the range of 780-850 Hv.
5. A lawnmower according to claim 2 wherein the base metal comprises steel and the hardened layer comprises a tungsten carbide/cobalt mixture.
6. A lawnmower according to claim 1 and substantially as herein described.
GB9119978A 1990-09-27 1991-09-19 Cylinder lawnmowers Expired - Fee Related GB2248165B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB909021040A GB9021040D0 (en) 1990-09-27 1990-09-27 Cylinder lawnmowers

Publications (3)

Publication Number Publication Date
GB9119978D0 GB9119978D0 (en) 1991-11-06
GB2248165A true GB2248165A (en) 1992-04-01
GB2248165B GB2248165B (en) 1994-01-12

Family

ID=10682836

Family Applications (2)

Application Number Title Priority Date Filing Date
GB909021040A Pending GB9021040D0 (en) 1990-09-27 1990-09-27 Cylinder lawnmowers
GB9119978A Expired - Fee Related GB2248165B (en) 1990-09-27 1991-09-19 Cylinder lawnmowers

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB909021040A Pending GB9021040D0 (en) 1990-09-27 1990-09-27 Cylinder lawnmowers

Country Status (1)

Country Link
GB (2) GB9021040D0 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2264033A (en) * 1992-02-12 1993-08-18 Atco Qualcast Ltd Hardened static blade for cylinder lawnmower.

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB875696A (en) * 1956-12-27 1961-08-23 Toro Mfg Corp Improvements in or relating to mowers
WO1981002967A1 (en) * 1980-04-14 1981-10-29 E Hixon Improved disc reel for mower
WO1991003923A1 (en) * 1989-09-15 1991-04-04 Ransomes Sims & Jefferies Limited Bottom blade for grass cutting unit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB875696A (en) * 1956-12-27 1961-08-23 Toro Mfg Corp Improvements in or relating to mowers
WO1981002967A1 (en) * 1980-04-14 1981-10-29 E Hixon Improved disc reel for mower
WO1991003923A1 (en) * 1989-09-15 1991-04-04 Ransomes Sims & Jefferies Limited Bottom blade for grass cutting unit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2264033A (en) * 1992-02-12 1993-08-18 Atco Qualcast Ltd Hardened static blade for cylinder lawnmower.
GB2264033B (en) * 1992-02-12 1994-06-01 Atco Qualcast Ltd Cylinder lawnmowers

Also Published As

Publication number Publication date
GB9021040D0 (en) 1990-11-07
GB2248165B (en) 1994-01-12
GB9119978D0 (en) 1991-11-06

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Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20100919