GB1406404A - Outboard drive for boats - Google Patents

Abstract

1406404 Outboard drive for a boat VOLVO PENTA AB 9 Jan 1973 1085/73 Heading B7V An outboard drive unit of the type comprising two parallel, upright, rigid drive shafts 3, 23 for transmitting torque to a horizontal propeller shaft 20 is constructed to facilitate adjustments ensuring equal torque division between the two drive shafts under maximum forward driving torque transmission. The main drive shaft 3 is rotatable in bearings 13, 14, 15 and carries at its lower end an integral bevel gear 16 which meshes with the teeth 17 of a dual bevel gear 18 which is splined to the prop shaft 20. Meshing with the other teeth 22 of gear 18 is a bevel gear 21 formed at the lower end of the auxiliary drive shaft 23 which is mounted in bearings similarly to shaft 3. Shaft 23 is driven from shaft 3 by meshed spur gear wheels 27 and 28 which have substantially zero clearance. Gear-wheel 27 is rigidly fixed to shaft 3 by splines 29 and by a nut 30 screwed down, on the threads 31 on shaft 3, tightly against gear-wheel 27. Gear-wheel 28 is internally tapered to fit the tapered upper portion 32 of shaft 23 where it is retained by a nut 33. Shaft 23 has in its upper end oil passages 35, 36 leading from the surface of the tapered portion 32 to the exposed end portion 37 of the shaft. Both shafts are arranged to receive an adjusting wrench; on shaft 3 splines 39 are used and on shaft 23, the flats 38 above nut 33. While shaft 23 and the lower portion of shaft 3 are torsionally rigid, the input portion 40 of shaft 3 may be formed as a torsion shaft. Method of adjustment.-(a) Nuts 30, 33 are tightened down against spur gear-wheels 27, 28; (b) propeller shaft 20 is clamped against rotation relative to housing 9; (c) wrenches are engaged on shafts 3, 23; (d) oil under high pressure is supplied through passages 35, 36 to shaft 23 to expand gear-wheel 28 and to form an oil film between the shaft and the gear-wheel to allow their relative rotation; (e) the wrenches are now rotated against each other with the wrench on shaft 3 tending to cause forward rotation of the propeller shaft 20 with a torque of exactly half the full-load torque and with the wrench on shaft 23 tending to cause opposite rotation with identical torque; (f) the oil pressure in passages 35, 36 is removed so that gear-wheel 28 contracts on to shaft portion 32 in its correct radial position.