GB1596435A

GB1596435A - Spindle assembly for gramophone record playing apparatus

Info

Publication number: GB1596435A
Application number: GB536978A
Authority: GB
Original assignee: TIEFENBRUN J
Current assignee: TIEFENBRUN J
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-08-26

Description

(54) SPINDLE ASSEMBLY FOR GRAMOPHONE RECORD PLAYING APPARATUS (71) I, JACK YAN TIEFENBRUN, a British subject, of 6, Paidmyre Crescent, Newton Mearns, Glasgow G77 5AG, Scotland, Great Britain, do hereby declare the invention, for which I pray that a patent may be granted to me. and the method by which it is to be performed. to be particularly described in and by the following statement:- This invention relates to a spindle assembly for gramophone record playing apparatus.

According to the present invention, there is provided a spindle assembly for mounting a gramophone turntable platter, said assembly comprising a bearing housing from which one end of a spindle projects and is adapted for mounting the platter, and in which the spindle is located for rotation relative to the housing and which has an internal tapered bearing surface, the spindle being correspondingly tapered, and a thrust bearing means located within the housing and comprising a plate and a point engaging said plate, the point being located at the tapered end of the spindle or in the housing and the plate being located in the housing or on the tapered end of the spindle respectively.

Preferably. the part of the thrust bearing means mounted in the housing is adjustable axially of said housing.

Preferably also. the point is formed an the spindle and the plate is mounted in the bearing housing.

Preferably also, the outer surface of the spindle is undercut intermediate its ends.

The plate may be mounted in an externally screw-threaded insert mating with internal screw threads in the bearing housing.

The plate may be mounted eccentrically in the insert.

An embodiment of the invention will be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is an elevation partly in section of a spindle assembly according to the present invention mounting a turntable platter.

Fig. 2 is an elevation of a spindle of the spindle assembly: Fig. 3 is a sectional elevation of a bearing housing of the spindle assembly; and Fig. 4 is an elevation of an insert of the spindle assembly.

Referring to the drawings, a spindle 10 of hardened, ground, superfinished tool steel has one end 12 adapted to mount a turntable platter 14 on a sub-chassis 16 of a gramophone record playing aparatus, the spindle having a record locating pin 13 at said end 12. The spindle 10 is rotatably mounted in a bearing housing 18 moulded in one piece from a self-lubricating plastics material, such as nylon or PTFE.

The bearing housing 18 has an internal tapered bearing surface 20. The spindle 10 is correspondingly tapered in the direction away from the end 12 mounting the platter 14. The angle of taper is, e.g. 10 to the longitudinal axis. The other end portion 22 of the spindle, i.e. the reduced diameter end portion, is formed with a bearing portion in the form of a fine bearing point 24. The fine bearing point preferably has a radius of the order of 100 thou.

The bearing portion 22 of the spindle bears against a hardened, ground, lapped high speed steel or carbide plate 26 serving as a thrust bearing pad for the spindle and pressed into a mild steel insert 28 which has external screw-threading 30 along the portion of its length remote from the end which holds the plate 26. The threading 30 of the insert mates with internal screw threads 32 in the outer part of an end portion 34 in the bearing housing 18 remote from the platter 14 whereby the insert 28 is axially adjustable in the housing 18. The portion of the insert 28 at the plate end has an annular channel into which an O-ring 38 is located to prevent seepage of oil from above as will be explained hereinafter. The plate 26 is preferably pressed eccentrically into the insert 28 and the end face of the plate is contacted by the point 24 of the spindle 10 and is substantially flush with the associated end face of the insert. The end portion of the insert 28 remote from the plate projects from the housing as shown in Fig. 1 and is lockable to the housing by a set-screw 40 in the associated end of the housing 18. The end face of said end portion has a slot 42 for engagement by a screwdriver blade.

The bearing housing 18 is filled with oil and the spindle is undercut intermediate its ends to present two bearing surfaces 44, 46 contacting the bearing surface 20 of the housing. The undercut portion of the spindle presents in conjunction with the bearing surface of the housing cavity 48 for retention of oil.

The end of the bearing housing remote from the insert has a flange portion 50 securable by self-tapping screws to the subchassis 16 of the record playing apparatus.

The thrust plate 26 may be mounted concentrically in the insert 28.

In a modification. not shown, the thrust plate is located at the tapered end of the spindle and the point is mounted in the insert. The plate is mounted on the nose of the finished spindle e.g. by the use of an adhesive and thereafter the outside diameter of the plate, if necessary, is ground down to below the surface of taper.

In a second embodiment, also not shown, the spindle assembly is reversed relative to the first embodiment, so that the bearing housing carries the platter and the spindle is fixedly mounted on the sub-chassis; thus the point of the spindle will underlie the plate on the inner end of the insert. In such an arrangement, the flange 50, for example, will not be on the housing, but on the spindle at the end 12 thereof. while the record locating pin 13 will be mounted on the housing at the end thereof in which the insert is located.

Also, the O-ring 38 will not be necessary on the insert but will be provided to prevent oil escaping from the lower end of the spindle.

The record locating pin is a cap which is removably mounted on the upper end of the bearing housing through an enlarged central aperture in the platter In this way the record can be located on the turntable or, when the cap is removed axial adjustment of the insert can be made using a screwdriver. Such adjustment would lift or lower the bearing housing relative to the spindle.

In a modification of this second embodiment, the point is mounted on the inner face of the insert and the plate is mounted on the tapered end of the spindle so that the point will overlie the thrust plate.

As rumble, which is objectionable in record playing apparatus, is caused particularly by gyration of the spindle point and is also a function of wear at the point of contact of the spindle with the thrust bearing, using the spindle assembly of the present invention maintains the smallest optimum area of contact, i.e. the point contact 24 so that gyration and wear, and thus rumble, are reduced to an absolute minimum and the platter 14 is not subjected to the forces which are generated in a bearing when same is running in a wear state. Gyration of the spindle point 24 and thus rumble and wear are also further reduced by virtue of the fact that tapering of the spindle 10 and of the bearingsurface 20 of the housing provides for a pre-determined clearance to be maintained between the spindle and said bearing surface, by axial adjustment of the insert 28, irrespective of small changes in or diameter variations of the spindle and/or of the bearing surface. This has the advantage that the clearance between the spindle 10 and the bearing surface 20 is infinitely adjustable to reduce gyration of the spindle point 24 to an absolute minimum and wear, if it should take place, at the point of contact between the spindle 10 and the thrust bearing plate 26 or between the other bearing surfaces 20 and 44, 46 is readily and simply compensated for by axial adjustment of the insert.

Where the thrust bearing plate 26 is mounted eccentrically of the insert 28, axial adjustment of the insert 28 will present a fresh bearing surface to the point 24 of the spindle 10, thus still further reducing wear and rumble of the bearing surfaces during operation of the turntable.

In lieu of a moulded one-piece bearing housing 18, the housing may be of mild steel lined with a self-lubricating plastics material, such as nylon or PTFE, providing the bearing surface for the spindle.

The external appearance of the bearing housing is not a feature of this invention and the housing may be of any suitable shape externally.

The angle of taper may be any suitable angle provided that it is the same for both the spindle and the internal bearing surface of the housing.

WHAT I CLAIM IS: 1. A spindle assembly for mounting a gramophone turntable platter, said assembly comprising a bearing housing from which one end of a spindle projects and is adapted for mounting the platter, and in which the spindle is located for rotation relative to the housing and which has an internal tapered bearing surface, the spindle being correspondingly tapered, and a thrust bearing means located within the housing and comprising a plate and a point engaging said plate, the point being located at the tapered end of the spindle or in the housing and the plate being located in the housing or on the tapered end of the spindle respectively.

2. An assembly as claimed in Claim 1, in which the part of the thrust bearing means mounted in the housing is adjustable axially of said housing.

3. An assembly as claimed in Claim 1 or 2, in which the point is formed on the spindle and the plate is mounted in the bearing housing.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. face of said end portion has a slot 42 for engagement by a screwdriver blade. The bearing housing 18 is filled with oil and the spindle is undercut intermediate its ends to present two bearing surfaces 44, 46 contacting the bearing surface 20 of the housing. The undercut portion of the spindle presents in conjunction with the bearing surface of the housing cavity 48 for retention of oil. The end of the bearing housing remote from the insert has a flange portion 50 securable by self-tapping screws to the subchassis 16 of the record playing apparatus. The thrust plate 26 may be mounted concentrically in the insert 28. In a modification. not shown, the thrust plate is located at the tapered end of the spindle and the point is mounted in the insert. The plate is mounted on the nose of the finished spindle e.g. by the use of an adhesive and thereafter the outside diameter of the plate, if necessary, is ground down to below the surface of taper. In a second embodiment, also not shown, the spindle assembly is reversed relative to the first embodiment, so that the bearing housing carries the platter and the spindle is fixedly mounted on the sub-chassis; thus the point of the spindle will underlie the plate on the inner end of the insert. In such an arrangement, the flange 50, for example, will not be on the housing, but on the spindle at the end 12 thereof. while the record locating pin 13 will be mounted on the housing at the end thereof in which the insert is located. Also, the O-ring 38 will not be necessary on the insert but will be provided to prevent oil escaping from the lower end of the spindle. The record locating pin is a cap which is removably mounted on the upper end of the bearing housing through an enlarged central aperture in the platter In this way the record can be located on the turntable or, when the cap is removed axial adjustment of the insert can be made using a screwdriver. Such adjustment would lift or lower the bearing housing relative to the spindle. In a modification of this second embodiment, the point is mounted on the inner face of the insert and the plate is mounted on the tapered end of the spindle so that the point will overlie the thrust plate. As rumble, which is objectionable in record playing apparatus, is caused particularly by gyration of the spindle point and is also a function of wear at the point of contact of the spindle with the thrust bearing, using the spindle assembly of the present invention maintains the smallest optimum area of contact, i.e. the point contact 24 so that gyration and wear, and thus rumble, are reduced to an absolute minimum and the platter 14 is not subjected to the forces which are generated in a bearing when same is running in a wear state. Gyration of the spindle point 24 and thus rumble and wear are also further reduced by virtue of the fact that tapering of the spindle 10 and of the bearingsurface 20 of the housing provides for a pre-determined clearance to be maintained between the spindle and said bearing surface, by axial adjustment of the insert 28, irrespective of small changes in or diameter variations of the spindle and/or of the bearing surface. This has the advantage that the clearance between the spindle 10 and the bearing surface 20 is infinitely adjustable to reduce gyration of the spindle point 24 to an absolute minimum and wear, if it should take place, at the point of contact between the spindle 10 and the thrust bearing plate 26 or between the other bearing surfaces 20 and 44, 46 is readily and simply compensated for by axial adjustment of the insert. Where the thrust bearing plate 26 is mounted eccentrically of the insert 28, axial adjustment of the insert 28 will present a fresh bearing surface to the point 24 of the spindle 10, thus still further reducing wear and rumble of the bearing surfaces during operation of the turntable. In lieu of a moulded one-piece bearing housing 18, the housing may be of mild steel lined with a self-lubricating plastics material, such as nylon or PTFE, providing the bearing surface for the spindle. The external appearance of the bearing housing is not a feature of this invention and the housing may be of any suitable shape externally. The angle of taper may be any suitable angle provided that it is the same for both the spindle and the internal bearing surface of the housing. WHAT I CLAIM IS:

1. A spindle assembly for mounting a gramophone turntable platter, said assembly comprising a bearing housing from which one end of a spindle projects and is adapted for mounting the platter, and in which the spindle is located for rotation relative to the housing and which has an internal tapered bearing surface, the spindle being correspondingly tapered, and a thrust bearing means located within the housing and comprising a plate and a point engaging said plate, the point being located at the tapered end of the spindle or in the housing and the plate being located in the housing or on the tapered end of the spindle respectively.

4. An assembly as claimed in any one of

Claims 1 to 3, in which the outer surface of the spindle is undercut intermediate its ends.

5. An assembly as claimed in any of Claims 1 to 4, in which the plate is mounted in an externally screw-threaded insert mating with internal screw threads in the bearing housing.

6. An assembly as claimed in Claim 4, in which the plate is mounted eccentrically in the insert.

7. An assembly as claimed in any one of Claims 1 to 6, in which the angle of taper of the housing bearing surface and of the spindle is 10 to the longitudinal axis thereof.

8. An assembly as claimed in any one of Claims 1 to 7, in which the spindle is adapted to carry the turntable platter.

9. An assembly as claimed in Claims 8, in which the bearing housing is adapted for fixed location on the chassis of a gramophone record playing apparatus.

10. An assembly as claimed in any one of Claims 1 to 7. in which the bearing housing is adapted to carry the turntable platter.

Il. An assembly as claimed in Claim 10, in which the spindle is adapted for location on the chassis of a gramophone record playing apparatus.

12. A gramophone record playing apparatus, wherein the turntable platter thereof is mounted on a spindle assembly as claimed in any one of the preceding claims.

13. A spindle assembly for mounting a gramophone turntable platter, substantially as hereinbefore described with reference to the accompanying drawings.