GB2146077A

GB2146077A - Self-aligning shaft system

Info

Publication number: GB2146077A
Application number: GB08323736A
Authority: GB
Inventors: Andras Tarcsafalvi
Original assignee: Magyar Optikai Muvek; Magyar Optikai Muevek
Current assignee: Magyar Optikai Muvek; Magyar Optikai Muevek
Priority date: 1983-09-05
Filing date: 1983-09-05
Publication date: 1985-04-11
Also published as: GB8323736D0; GB2146077B

Abstract

A self-aligning system comprises a rotatable shaft (10), a housing (9) in which said shaft is mounted, upper and lower opposing spherical segments (1,4) integral with or attached to the housing, and upper and lower sets of balls (2,5) held between the respective segments (1,4) and recesses (3,6) on the shaft, the lower spherical segments being compressed against the set of balls (5) by a tensioning element (7). The system may be used in a gyroscopic theodolite. <IMAGE>

Description

SPECIFICATION Self-aligning shaft system This invention relates to a self-aligning shaft system forthe bearing of a rotating unit following the movement of the pendulum system of gyroscopic theodolites with short period of oscillation and two degrees of freedom used for azimuth determination.

The bearing of a rotating unit following the movement of a pendulum system of gyroscopic theodolites with short period of oscillation and two degrees of freedom is selected to be self-aligning and free from play.

Numerous prior art shafts with ball-bearings, sliding bearings or with combinations thereof have been proposed.

One of them is, for instance, a shaft with two sets of balls. One set of balls carries the vertical load and the other one is pressed between running surfaces formed on an axially movable sleeve biased by spring force and pulled onto the shaft and on the stationary part, respectively. One of the running surfaces is cylindrical, the other one is conical.

There are other shafts where the direction of the shaft is ensured by a set of balls running between flat surfaces on the stationary and rotating parts, and a centralization is ensured by a cylindrical band sleeve a pin surface formed between the stationary and rotating parts, while the axial displacement is restricted with fitting or play.

The drawback of these shaft systems is that they are accurate only within very narrow limits, or owing to the manufacturing tolerances, have axial or radial play. The value of the bearing clearance varies because different structural materials are used, taking into consideration the extreme temperatures arising during work with the field instruments.

The self-aligning shaft system according to the invention reduces the disadvantages of the known solutions. According to the invention, two spherical segments and two opposite corner surfaces of rotation are formed on the housing and rotating unit, sets of balls are arranged between the spherical segments and corner surfaces of rotation, and at least one tensioning element is provided in the apparatus for compression of the sets of balls.

Figure 1 shows a preferred embodiment of the invention, by way of example.

Sets of balls 2 and 5 are arranged between spherical segments 1 and 4formed on a housing 9 and the surfaces of rotation of shaft 10 constituted by corners 3 and 6, the housing 9 and shaft 10 forming a shaft system. A tensioning element 7 formed on the housing 9 presses the spherical segment surfaces through the set of balls to the corner surfaces of rotation of the shaft.

In this arrangement the rotating shaft 10 is able to turn around the axis of rotation formed by spherical centres 8, 11 accurately and free from play even under extreme temperature conditions. The clearance-free condition is ensured by the elastic tensioning of element 7. From an operational point of view, an equivalent to this arrangement is one where the spherical segment surfaces are formed on the shaft and the corner surfaces of rotation on the housing. A combination of the two embodiments also yields the said advantages.

1. Self-aligning shaft system, particularly for gyroscopic theodolites with two degrees of freedom and short period of oscillation, provided with housing and rotating unit carried on bearing and following the movement of the pendulum system, wherein two spherical segments and two opposite surfaces of rotation are formed on the housing and the rotary unit, sets of balls or equivalent rolling elements are arranged between the spherical segments and surfaces of rotation, and at least one tensioning element is provided to bias the segments and/or surfaces in the sense of compression of the sets of balls or rolling elements.

2. A self-aligning shaft system substantially as herein described with reference to and as shown in the accompanying drawing.

3. A gyroscopictheodolite including a selfaligning shaft system according to claim 1 or claim 2.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Self-aligning shaft system This invention relates to a self-aligning shaft system forthe bearing of a rotating unit following the movement of the pendulum system of gyroscopic theodolites with short period of oscillation and two degrees of freedom used for azimuth determination. The bearing of a rotating unit following the movement of a pendulum system of gyroscopic theodolites with short period of oscillation and two degrees of freedom is selected to be self-aligning and free from play. Numerous prior art shafts with ball-bearings, sliding bearings or with combinations thereof have been proposed. One of them is, for instance, a shaft with two sets of balls. One set of balls carries the vertical load and the other one is pressed between running surfaces formed on an axially movable sleeve biased by spring force and pulled onto the shaft and on the stationary part, respectively. One of the running surfaces is cylindrical, the other one is conical. There are other shafts where the direction of the shaft is ensured by a set of balls running between flat surfaces on the stationary and rotating parts, and a centralization is ensured by a cylindrical band sleeve a pin surface formed between the stationary and rotating parts, while the axial displacement is restricted with fitting or play. The drawback of these shaft systems is that they are accurate only within very narrow limits, or owing to the manufacturing tolerances, have axial or radial play. The value of the bearing clearance varies because different structural materials are used, taking into consideration the extreme temperatures arising during work with the field instruments. The self-aligning shaft system according to the invention reduces the disadvantages of the known solutions. According to the invention, two spherical segments and two opposite corner surfaces of rotation are formed on the housing and rotating unit, sets of balls are arranged between the spherical segments and corner surfaces of rotation, and at least one tensioning element is provided in the apparatus for compression of the sets of balls. Figure 1 shows a preferred embodiment of the invention, by way of example. Sets of balls 2 and 5 are arranged between spherical segments 1 and 4formed on a housing 9 and the surfaces of rotation of shaft 10 constituted by corners 3 and 6, the housing 9 and shaft 10 forming a shaft system. A tensioning element 7 formed on the housing 9 presses the spherical segment surfaces through the set of balls to the corner surfaces of rotation of the shaft. In this arrangement the rotating shaft 10 is able to turn around the axis of rotation formed by spherical centres 8, 11 accurately and free from play even under extreme temperature conditions. The clearance-free condition is ensured by the elastic tensioning of element 7. From an operational point of view, an equivalent to this arrangement is one where the spherical segment surfaces are formed on the shaft and the corner surfaces of rotation on the housing. A combination of the two embodiments also yields the said advantages. CLAIMS