Patent US3757899A successfully refreshed from Google Patents.
US3757899A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Double mast side loader lift truck and double actuator balancing
Assignee: C AND M MANUF CO
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Filing: 1971-03-12
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Granted: 1973-09-11
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Expires: 1991-03-12
Abstract
Abstract A side loader lift truck has a carriage which moves vertically between fore and aft spaced and unconnected masts. Forks on the carriage move laterally to either side of the masts through the open space between the masts. To prevent carriage tilting and jamming caused by a lift cylinder at one end of the carriage overrunning its opposite counterpart, a supply valve for the overrunning actuator is cut off until the other actuator catches up. The balancing or overrunning prevention is effected by connecting valve bodies to pistons, movable mast portions, or the carriage. Control spools moving within the valve bodies are interconnected by parallel chains and sprockets which move with an interconnecting shaft. The shaft is biased initially in an up or down direction, biasing the valve spools in the up or down position. When the carriage is being raised, excessive upward motion of one valve body carries the body over the spool, cutting off further supply through that valve to the actuator until the synchronizing shaft and chain return the valve spool to its predetermined position.
Inventors
- 👤 R Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:46
CPC Classifications
B; B66; B66F; B66F9/00; B66F9/06; B66F9/07
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
192 words
Lift truck apparatus comprising first and second spaced masts and first and second hydraulic actuators mounted adjacent said first and second masts, carriage means connected to the first and second masts for movement therealong and operatively connected to the actuators for being driven thereby, first and second valves connected to a common hydraulic power unit and mounted respectively adjacent the first and second actuators, each valve controlling the corresponding actuator during both upward and downward movement of the actuators, the valves having first portions connected to movable portions of the actuators, masts or carriage and having second portions movable with respect to the first portion, whereby movement of a second portion with respect to the first portion changes operational condition of a valve, first and second operator means connected respectively to movable portions of the first and second valves and synchronizing means connected to the operators whereby relative movement of a first mast, first actuator or adjacent carriage portion with respect to the second mast, second actuator or a related carriage portion produces relative movement between first and second portions of at least one valve thereby changing operational condition of the valve.
Claim 2
Dependent Claim
192 words
Lift truck apparatus comprising first and second spaced masts and first and second hydraulic actuators mounted adjacent said first and second masts, carriage means connected to the first and second masts for movement therealong and operatively connected to the actuators for being driven thereby, first and second valves connected to a common hydraulic power unit and mounted respectively adjacent the first and second actuators, each valve controlling the corresponding actuator during both upward and downward movement of the actuators, the valves having first portions connected to movable portions of the actuators, masts or carriage and having second portions movable with respect to the first portion, whereby movement of a second portion with respect to the first portion changes operational condition of a valve, first and second operator means connected respectively to movable portions of the first and second valves and synchronizing means connected to the operators whereby relative movement of a first mast, first actuator or adjacent carriage portion with respect to the second mast, second actuator or a related carriage portion produces relative movement between first and second portions of at least one valve thereby changing operational condition of the valve.
Claim 3
Dependent Claim
179 words
Lift truck apparatus comprising first and second spaced masts and first and second hydraulic actuators mounted adjacent said first and second masts, carriage means connected to the first and second masts for movement therealong and operatively connected to the actuators for being driven thereby, first and second valves mounted respectively adjacent the first and second actuators, the valves having first portions comprising spool valve bodies connected to movable portions of the actuators, masts or carriage and having second portions comprising spool valve pistons mounted within the bodies for movement therein, whereby movement of a second portion with respect to the first portion changes operational condition of a valve, first and second operator means connected respectively to the spool valve pistons of the first and second valves and synchronizing means comprising a shaft having fixed radial extensions connected to the operators whereby relative movement of a first mast, first actuator or adjacent carriage portion with respect to the second mast, second actuator or a related carriage portion produces relative movement between first and second portions of at least one valve.
Claim 4
Dependent Claim
179 words
Lift truck apparatus comprising first and second spaced masts and first and second hydraulic actuators mounted adjacent said first and second masts, carriage means connected to the first and second masts for movement therealong and operatively connected to the actuators for being driven thereby, first and second valves mounted respectively adjacent the first and second actuators, the valves having first portions comprising spool valve bodies connected to movable portions of the actuators, masts or carriage and having second portions comprising spool valve pistons mounted within the bodies for movement therein, whereby movement of a second portion with respect to the first portion changes operational condition of a valve, first and second operator means connected respectively to the spool valve pistons of the first and second valves and synchronizing means comprising a shaft having fixed radial extensions connected to the operators whereby relative movement of a first mast, first actuator or adjacent carriage portion with respect to the second mast, second actuator or a related carriage portion produces relative movement between first and second portions of at least one valve.
Claim 5
Dependent Claim
44 words
The apparatus of claim 2 further comprising a biasing means connected to the synchronizing means for moving the synchronizing means in one of two directions thereby moving the second valve portions with respect to the first valve portions for creating a predetermined valve condition.
Claim 6
Dependent Claim
74 words
The apparatus of claim 1 wherein the first valve portions comprise spool valve bodies connected to move with respective actuators and where the second valve elements comprise spool valve pistons mounted within the bodies for movement therein, wherein the operators comprise flexible means connected to the spool valve pistons, and wherein the synchronizing means comprises a shaft having fixed sprockets connected to the flexible means for preventing excessive relative movement between the flexible means.
Claim 7
Dependent Claim
49 words
The apparatus of claim 2 further comprising a hydraulic pressure pump, a flow divider connected to the pressure pump for receiving hydraulic fluid therefrom and for dividing flow between first and second hydraulic lines which are connected through the first and second valves to the first and second actuators.
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) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |