US 4,199,999 A · Ball-type mechanical transmission

Abstract

A low-friction, light-load, low-cost mechanical transmission for converting rotary motion to linear motion, comprising an elongate screw shaft having a rolled thread groove, a multi-part follower nut comprising a sleeve having a through hole constituting a ball socket and a cylindrical jacket encircling the sleeve, there being a thread-engaging ball disposed in the socket and engaging the walls of the thread groove. The bore of the jacket has a hard surface which engages and provides a back-up for the ball as the latter traverses the length of the screw shaft. The sleeve is held captive within the jacket by a pair of locking rings received in annular grooves in the bore of the latter. Surrounding the nut is a tubular housing. Anti-friction sleeve bearings on the exterior of the jacket slidably engage the inner surface of the housing to enable the nut to move freely therein as the screw shaft is rotatably driven. A tubular connector member is telescopically received in the housing and is immovably secured to the jacket by one of the locking rings which hold the sleeve and jacket assembled. An additional bearing between the housing and connector member maintains the latter centralized, thereby eliminating binding or seizing. It is particularly adapted for light-to-moderate load applications, including a conversion in the steering mechanism of boats, between the turning movement of the wheel and the reciprocative movement of the rudder.

Claims24

Dependent claims

A light-load mechanical actuator device for applying reciprocating forces to a machine part, comprising in combination:

(a) an elongate screw shaft having a helical thread characterized by a rounded bottom trough,
(b) a shaft-engaging ball disposed in said thread,
(c) a sleeve encircling said screw shaft, having an opening constituting a socket extending between its inner and outer walls and in which the ball is received, said sleeve having spaced-apart portions and internal annular slide bearings carried by said portions and engaging the screw shaft,
(d) a substantially cylindrical jacket encircling and closely fitting said sleeve and having its bore engaged with and providing a back-up surface for said ball, said jacket extending beyond the ends of the sleeve,
(e) locking rings disposed in the bore of the jacket, one of said rings engaging one end of the sleeve,
(f) a tubular connector member in which the shaft is received, said connector member having a shouldered extremity disposed within said jacket and engaged by the other locking ring,
(g) anti-friction slide bearings carried exteriorly at the ends of said jacket, and
(h) a tubular housing surrounding said jacket and having its bore engaged by said anti-friction bearings, said anti-friction bearings enabling sliding movement of the sleeve and jacket to occur within the housing as the screw shaft is rotatably driven.

5 more elements

A light-load mechanical transmission for converting rotary to linear motion, comprising in combination:

(a) an elongate screw shaft having a generally helical thread groove,
(b) a nut having a through bore to receive the screw,
(c) a ball driving element carried by the nut and engageable with the walls of the thread groove,
(d) anti-friction slide bearings carried in the bore of the nut and disposed at spaced-apart locations therein, for sliding engagement with the screw shaft,
(e) a tubular housing having an inner wall surface, said housing substantially completely enclosing the nut,
(f) an annular slide bearing disposed between the nut and the inner wall surface of the housing to enable low-resistance sliding movement to occur between the nut and the housing,
(g) bearing means carried by said housing and engageable with the screw shaft for maintaining the latter substantially centralized with respect to the housing as the nut moves with respect thereto,
(h) a tubular connector member telescopically receivable in said housing and having a portion projecting through an open end thereof, and
(i) means for securing said connector member to the nut such that force from the latter is transmitted to the connector member for performing useful work.

6 more elements

Dependencies are inferred from the claim text.

Ball-type mechanical transmission

Life of this patent

Ball-type mechanical transmission

Life of this patent

Abstract

Claims24