GB835571A - Improvements in or relating to lawn mowers - Google Patents

Abstract

835,571. Lawn-mowers. SUFFOLK IRON FOUNDRY (1920) Ltd. Dec. 12, 1957 [Dec. 12, 1956], No. 37981/56. Class 6(2). In a motor driven lawn-mower of the kind in which the prime mover drives both the cutting cylinder and two ground wheels or roller-parts, the ground wheels or roller-parts are driven through differential gearing comprising a planet carrier in operative connection with the prime mover and at least one planet gear rotatable on a stub shaft carried by the planet carrier and meshing with two gears connected respectively to the two ground wheels or roller-parts, means being provided for resisting the rotational movement of the or each planet gear about its axis. According to the preferred embodiment, the mower comprises a vertically adjustable roller 16 for altering the depth of cut of the cutting cylinder 17 which in turn is adjustable towards or away from a ledger blade 27, and two rollerparts 36 mounted on a common shaft 14 for moving the mower forwardly over the ground. The prime mover may comprise either an electric motor or an internal combustion engine and drives the cutting cylinder via a shaft 34, sprocket wheels 32 and 33 and chain 31, the drive to the roller shaft 14 being derived from the sprocket wheel 33 through a further system of chains and sprocket wheels and including a dog clutch 72 operable by means of the lever 75, whereby the drive to the rollerparts may be disconnected whilst maintaining the drive to the cutting cylinders. The adjacent end plates 39 of the two roller-parts 36 are dished inwardly to provide a housing for a planet carrier 51 which is rigidly connected to the shaft 14, holes being bored in the arms 52 of the carrier to receive stub shafts 54 on each of which a planet gear 55 is rotatably mounted to mesh with rings of bevel gear teeth mounted one on each end plate 39. Rotation of the planet-gears about their respective stub shafts is restricted by means of friction pads 58 and 59 urged into engagement with the gears by means of nuts 63 threaded on the stub shafts, so that when one roller-part is out of engagement with the ground, whereas normally that part in contact with the ground will remain stationary and the raised part will spin as a result of the rotation of the planet gears about their respective stub shafts, such rotation of the planet gears being restricted, both roller-parts will still be positively driven.