US3910649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic device for stretching the tracks of a tracked vehicle
Assignee: Glamox AS
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Filing: 1974-04-25
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Granted: 1975-10-07
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Expires: 1994-04-25
Abstract
Abstract A hydraulic device for stretching the tracks of tracked vehicles such as caterpillar tractors, crawlers and the like, with a closed circuit hydrostatic power transmission system, and in which the tracks are stretched by means of a hydraulic cylinder acting on the truck big idler. The stretching cylinder is communicating with that side of the closed hydrostatic transmission circuit which has high pressure when the vehicle is moving backward (rear mounted bull wheels) and feed pressure when the vehicle is moving forward. The stretching of the track(s) will then be proportional to the resistance against vehicle motion during backward driving preventing buckling of the ground engaging part of the track. Thus the track stretching is always in accordance with the requirements, excessive stretching is avoided and track wear substantially reduced.
Inventors
- 👤 Bjorn Roskaft
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 03:31
CPC Classifications
B; B62; B62D; B62D55/00; B62D55/08; B62D55/30
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
230 words
A hydraulic track stretching system for use in a tracked vehicle of the type including at least one track system comprising a track passing around a bull wheel and an idler; and a closed circuit hydrostatic power transmission system operatively coupled to said bull wheel for alternatively driving said bull wheel in a first direction moving the lower run of said track from said idler to said bull wheel, driving said bull wheel in a second direction moving said lower track run from said bull wheel to said idler, or placing said bull wheel in a neutral position; said closed circuit hydrostatic power transmission system having a portion maintained at a higher drive pressure when said bull wheel is driven in said second direction and maintained at a lower feed pressure when said bull wheel is driven in said first direction or placed in said neutral position; said track stretching system comprising: a hydraulic stretching cylinder having a piston therein, said piston having a rod connected to said idler, said piston and rod being movable in response to fluid pressure in said cylinder toward said idler and thereby comprising means for moving said idler away from said bull wheel; and means for hydraulically connecting said cylinder with said portion of said closed circuit hydrostatic power transmission system and for maintaining said cylInder pressure proportional to the pressure in said portion.
Claim 2
Dependent Claim
230 words
A hydraulic track stretching system for use in a tracked vehicle of the type including at least one track system comprising a track passing around a bull wheel and an idler; and a closed circuit hydrostatic power transmission system operatively coupled to said bull wheel for alternatively driving said bull wheel in a first direction moving the lower run of said track from said idler to said bull wheel, driving said bull wheel in a second direction moving said lower track run from said bull wheel to said idler, or placing said bull wheel in a neutral position; said closed circuit hydrostatic power transmission system having a portion maintained at a higher drive pressure when said bull wheel is driven in said second direction and maintained at a lower feed pressure when said bull wheel is driven in said first direction or placed in said neutral position; said track stretching system comprising: a hydraulic stretching cylinder having a piston therein, said piston having a rod connected to said idler, said piston and rod being movable in response to fluid pressure in said cylinder toward said idler and thereby comprising means for moving said idler away from said bull wheel; and means for hydraulically connecting said cylinder with said portion of said closed circuit hydrostatic power transmission system and for maintaining said cylInder pressure proportional to the pressure in said portion.
Claim 3
Dependent Claim
29 words
A system as claimed in claim 1, wherein said connecting means further includes means for regulating said cylinder pressure and for absorbing oscillations in said pressure in said portion.
Claim 4
Dependent Claim
19 words
A system as claimed in claim 2, wherein said regulating means comprises a fixed and an adjustable throttle valve.
Claim 5
Dependent Claim
15 words
A system as claimed in claim 2, wherein said oscillation absorbing means comprises an accumulator.
Claim 6
Dependent Claim
18 words
A system as claimed in claim 4, wherein said oscillation absorbing means further comprises a throttle nonreturn valve.
Claim 7
Dependent Claim
17 words
A system as claimed in claim 2, wherein said oscillation absorbing means comprises a throttle non-return valve.
Claim 8
Dependent Claim
36 words
A system as claimed in claim 2, wherein said regulating means comprises shut off means for maintaining a predetermined minimum pressure in said stretching cylinder when said pressure in said portion drops below said minimum pressure.
Claim 9
Dependent Claim
26 words
A system as claimed in claim 7, wherein said shut off means comprises a two port valve operable in response to said pressure in said portion.
Claim 10
Dependent Claim
19 words
A system as claimed in claim 8, wherein said two port valve includes means for allowing manual operation thereof.
Claim 11
Dependent Claim
225 words
In a tracked vehicle of the type including at least one track system comprising a track passing around a bull wheel and an idler; a closed circuit hydrostatic power transmission system operatively coupled to said bull wheel for alternatively driving said bull wheel in a first direction moving the lower run of said track from said idler to said bull wheel, driving said bull wheel in a second direction moving said lower track run from said bull wheel to said idler, or placing said bull wheel in a neutral posistion; said closed circuit hydrostatic power transmission system having a portion maintained at a higher drive pressure when said bull wheel is driven in said second direction and maintained at a lower feed pressure when said bull wheel is driven in said first direction or placed in said neutral position; and a track stretching system including a hydraulic stretching cylinder having a piston therein, said piston having a rod connected to said idler, said piston and rod being movable in response to fluid pressure in said cylinder toward said idler and thereby comprising means for moving said idler away from said bull wheel; the improvement comprising: means for hydraulically connecting said cylinder with said portion of said closed circuit hydrostatic power transmission system and for maintaining said cylinder pressue proportional to the pressure in said portion.
Claim 12
Dependent Claim
225 words
In a tracked vehicle of the type including at least one track system comprising a track passing around a bull wheel and an idler; a closed circuit hydrostatic power transmission system operatively coupled to said bull wheel for alternatively driving said bull wheel in a first direction moving the lower run of said track from said idler to said bull wheel, driving said bull wheel in a second direction moving said lower track run from said bull wheel to said idler, or placing said bull wheel in a neutral posistion; said closed circuit hydrostatic power transmission system having a portion maintained at a higher drive pressure when said bull wheel is driven in said second direction and maintained at a lower feed pressure when said bull wheel is driven in said first direction or placed in said neutral position; and a track stretching system including a hydraulic stretching cylinder having a piston therein, said piston having a rod connected to said idler, said piston and rod being movable in response to fluid pressure in said cylinder toward said idler and thereby comprising means for moving said idler away from said bull wheel; the improvement comprising: means for hydraulically connecting said cylinder with said portion of said closed circuit hydrostatic power transmission system and for maintaining said cylinder pressue proportional to the pressure in said portion.
Claim 13
Dependent Claim
28 words
The improvement claimed in claim 10, wherein said connecting means further includes means for regulating said cylinder pressure and for absorbing oscillations in said pressure in said portion.
Claim 14
Dependent Claim
18 words
The improvement claimed in claim 11, wherein said regulating means comprises a fixed and an adjustable throttle valve.
Claim 15
Dependent Claim
14 words
The improvement claimed in claim 11, wherein said oscillation absorbing means comprises an accumulator.
Claim 16
Dependent Claim
17 words
The improvement claimed in claim 13, wherein said oscillation absorbing means further comprises a throttle non-return valve.
Claim 17
Dependent Claim
16 words
The improvement claimed in claim 11, wherein said oscillation absorbing means comprises a throttle non-return valve.
Claim 18
Dependent Claim
35 words
The improvement claimed in claim 11, wherein said regulating means comprises shut off means for maintaining a predetermined minimum pressure in said stretching cylinder when said pressure in said portion drops below said minimum pressure.
Claim 19
Dependent Claim
25 words
The improvement claimed in claim 16, wherein said shut off means comprises a two port valve operable in response to said pressure in said portion.
Claim 20
Dependent Claim
18 words
The improvement claimed in claim 17, wherein said two port valve includes means for allowing manual operation thereof.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-06 | 1979-04-07 | 1979-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-06 | 1983-04-07 | 1983-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-06 | 1987-04-07 | 1987-10-07 | $7700.00 | Window Closed / Lapsed |