Grass Cutters - Tractor mounted
Rotary cutters also known as slashers, bossiekappers or haycutters are widely used to cut veld grass and crop grasses such as eragrostis. They are defined by their cutting width ranging from 1M to 3M.
Generally a smallholder would make use of 1, 1.2 & 1.5M cutters. The cutter is hitched to the tractors three point linkage and driven by a PTO (Power take off) shaft sized to suit the implement.
A standard rotary cutter is dragged by the tractor and runs on a set of skid liners. A good quality slasher has four sturdy blades and a flail plate of at least 10mm thick bennox steel. The blades fit between the flail plate and a strut to swing back when hitting an obstacle.
Gearbox rated in KW
Hub assembly
Flail plate
The gearbox is sized & rated in KW. The larger the cutter the higher the KW rating. Also taken into account is the duty cycle of the cutter. IE a smallholder cutting twice a year would choose a machine "light duty" with a small gearbox and the commercial cutter a more robust gearbox with a higher KW rating. The gearbox is lubricated by oil inside. Typically there is a breather to prevent pressure building up inside the box, a filler plug & a level plug located midway on the side of the casting. Two oil seals, one on the input shaft and one on the output side. Gearboxes normally use a SAE 140 grade oil however the oil seal on the output shaft is vunerable to damage by grass and wire picked up during cutting. In our workshop we use Dimol Loader grease (Similar to a cars CV joint grease) Alternatively mix a thick but pourable coctail of multipurpose grease and oil. If the oil seal is damaged there will not be a sudden loss of oil.

The power take off shaft (PTO) is sized in series 1,2,3,4 etc. Typically a 1metre slasher will use a series 4 shaft & a 1.5metre slasher a series 6 shaft. The shaft consists of two universal joints and tubing which slides in & out as the cutter moves. The shaft is encased in a cover which, using the chains supplied, runs inside whilst the cover remains stationary. Grease points on the universal joint should be serviced regularly. The retaining clips must be inspected for wear as it is extremely dangerous when a rotating shaft comes adrift.
Chains attached to tractor & slasher to ensure cover remains stationary
Overun (Ratchet) clutch. Fitted to a PTO shaft when a tractor has a single clutch. It prevents the cutters momentum from pushing the tractor.
Slip clutch. Two clutch plates "slip" when an obstacle is struck protecting both cutter gaearbox & tractor. Tension is set by adjusting springs.
Never fit a PTO shaft whilst the tractor engine is running. Always ensure tractors PTO selector is disengaged before starting, undue stress is placed on starter motor when it is forced to turn both motor & implement. Set the tractors hydraulic lift controls that when the cutter is lifted the PTO shaft does not rub on the cutter deck. See cutter safety
The sole purpose of these chains is to lift the cutter off the gound. When lowered the chains should be "slack"
Never stand close to a cutter when in operation. Sit on the tractor & do not allow anyone to be behind the machine whilst cutting. The blades are capable of throwing heavy objects out of the rear. See cutter safety
Haycutters are a variation of the standard slasher with an additional 300mm added to the deck. Specialised blades throw the grass into a windrow for easy baling.
Rollermowers are a variation of the standard slasher fitted with rollers front & back with specialised blades which give a finish to lawn as a normal lawnmower would.
Blower mowers are a more advanced rollermower with a chute which cuts grass to a very fine finish and collects the cuttings in a bag.
Cutter Applications
Rotary slashers are suitable for all types of veld grass and certain crop grasses such as eragrostis.
Haycutters are used as above with the advantage of placing grass in a windrow for easy raking and baling.
Rollermowers are used on lawn grass and fine veld grass where surfaces are smooth.
Blowermowers are used on lawns & sports fields.
Rotary cutters fitted with a wheel are not suitable for harsh South African conditions

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Agriline Diesel cc is a registered company in South Africa : Reg no CK 2010/044705/23 | Registered Office: Shop 4 Kenmare Mall, Kenmare Krugersdorp 1739. Original equipment manufacturers names and parts numbers are quoted for reference purposes only and are not intended to suggest that our replacement parts are made by the original equipment manufacturer.