Gearbox for a rack and pinion linear transmission and drillstand including a gearbox and a rack

Patent metadata

Field	Value
Publication number	US-10704653-B2
Application number	US-201616091762-A
Country	US
Kind code	B2
Filing date	Apr 6, 2016
Priority date	Apr 6, 2016
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

A gearbox for a rack ( 6 ) and pinion ( 4 ) linear transmission, said gearbox further including—a reduction gear train ( 1 - 4 ) having at least a first ( 1 ), a second ( 2 ), a third ( 3 ), and a fourth gear wheel ( 4 ), where the fourth gear wheel is the pinion ( 4 ) for rotary engagement with the rack ( 6 ); a rotary input shaft ( 7 ) operatively connected to the gear train ( 1 - 4 ) to effect a linear relative movement between the rack ( 6 ) and the pinion ( 4 ); and an intermediate shaft ( 8 ) on which the first ( 1 ) and the second ( 2 ) gear wheel are fixed; the third gear wheel ( 3 ) being fixed on the input shaft ( 7 ), the fourth gear wheel ( 4 ) being journalled to enable it to rotate freely on the input shaft ( 7 ) and constituting the pinion ( 4 ), and the first gear wheel ( 1 ) and the fourth gear wheel ( 4 ) being in constant meshing engagement with each other.

First claim

The invention claimed is:

1. A gearbox for a rack and pinion linear transmission, said gearbox including
a reduction gear train having at least a first gear wheel, a second gear wheel, a third gear wheel, and a fourth gear wheel, where the fourth gear wheel is the pinion for rotary engagement with a rack;
a rotary input shaft operatively connected to the gear train to effect a linear relative movement between the rack and a pinion; and
an intermediate shaft on which the first and the second gear wheels are fixed;
wherein:
the third gear wheel is fixed on the input shaft, and the fourth gear wheel is journalled on the input shaft to enable the fourth gear wheel to rotate freely relative to the input shaft, and the first gear wheel and the fourth gear wheel are in constant meshing engagement with each other.

2. The gearbox as claimed in claim 1 , wherein the first gear wheel and the third gear wheel have a first identical number of teeth, and the second gear wheel and the fourth gear wheel have a second identical number of teeth.

3. The gearbox as claimed in claim 1 , wherein the first gear wheel has fewer teeth than the third gear wheel, and the fourth gear wheel has more teeth than the second gear wheel.

4. The gearbox as claimed in claim 1 , wherein the first, second, third and fourth gear wheels are spur gears.

5. The gearbox as claimed in claim 1 , wherein the first, second, third and fourth gear wheels are helical gears.

6. The gearbox as claimed in claim 1 , wherein the fourth gear wheel is journalled on the input shaft by means of a plain bearing.

7. The gearbox as claimed in claim 1 , wherein an additional shaft is provided, on which a fifth gear wheel is mounted, and wherein the input shaft drives the third gear wheel that is fixed on the input shaft, the third gear wheel is in meshing engagement with the second gear wheel and thereby also drives the first gear wheel, the first and the second gear wheels both being fixed to the intermediate shaft, and the first gear wheel is in meshing engagement with the fifth gear wheel as well as with the fourth gear wheel which fourth gear wheel rotates freely but is axially fixed on the input shaft, wherein both of the fourth gear wheel and the fifth gear wheel constitute pinions, so that the pinions comprised by the fourth gear wheel and the fifth gear wheel can engage the rack simultaneously.

8. The gearbox as claimed in claim 1 , wherein the second gear wheel and the third gear wheel are in constant meshing engagement with each other.

9. The gearbox as claimed in claim 1 , wherein the fourth gear wheel and the input shaft are displaceable relative to each other between two positions, and a locking device is provided for locking the fourth gear wheel to the input shaft at one of the two positions but permitting the fourth gear wheel and the input shaft to rotate freely relative to each other in the other of the two positions.

10. The gearbox as claimed in claim 9 , wherein the fourth gear wheel is axially fixed in the gearbox and constitutes the pinion, while the input shaft is axially displaceable in the gearbox.

11. The gearbox as claimed in claim 9 , wherein the locking device comprises a locking member having a portion projecting radially from the input shaft, and a side of the fourth gear wheel has a recess matching said portion of the locking member.

12. The gearbox as claimed in claim 11 , wherein the locking member is a locking pin.

13. The gearbox as claimed in claim 9 , wherein a mechanism is provided for displacing the input shaft between said two positions.

14. The gearbox as claimed in claim 9 , characterized by having two reduction ratios, including:
a first reduction ratio where the fourth gear wheel is locked to the input shaft; and
a second reduction ratio where the input shaft drives the third gear wheel that is fixed on the input shaft, the third gear wheel in turn driving the second gear wheel and thereby also the first gear wheel, both the first gear wheel and the second gear wheel being fixed to the intermediate shaft, and the first gear wheel driving the fourth gear wheel that rotates freely on the input shaft, so that the gearbox is a two-speed gearbox.

15. The gearbox as claimed in claim 9 , wherein an additional shaft is provided carrying a fifth gear wheel, and wherein the first gear wheel is in a constant meshing engagement with the fourth gear wheel and the fifth gear wheel, and both of the fourth and the fifth gear wheels constitute pinions that can be set in simultaneous meshing engagement with the rack.

16. The gearbox as claimed in claim 15 , wherein the fifth gear wheel is journalled on the additional shaft via a plain bearing.

17. A drill stand including a drill column supporting a rack running along the drill column, and a carriage arranged on the drill column, the carriage including a gearbox engaging the rack by a rack and pinion transmission for movement up and down the rack, wherein the rack and pinion transmission is provided by the gearbox and rack according to claim 1 .

Assignees

• Husqvarna Ab

Inventors

• Almqvist Torbjörn
• Grennhag David

Classifications

• B25H1/0064 Primary

  Stands attached to the workpiece · CPC title

• F16H19/043

  for converting reciprocating movement in a continuous rotary movement or vice versa, e.g. by opposite racks engaging intermittently for a part of the stroke · CPC title

• F16H2200/0034

  the gear ratios comprising two forward speeds · CPC title

• F16H3/083

  with radially acting and axially controlled clutching members, e.g. sliding keys · CPC title

• B25H1/0042

  Stands (B25H1/0071 takes precedence) · CPC title