Beds – Invalid bed or surgical support – Vertically movable support for whole body of user
Patent
1996-04-24
1997-12-30
Grosz, Alexander
Beds
Invalid bed or surgical support
Vertically movable support for whole body of user
5614, 254 93R, A61G 705, A61G 300
Patent
active
057016186
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a hydraulic system for hydraulically actuating an ambulance lifting table. In particular, the present invention deals with a hydraulic system for hydraulically actuating a vertically adjustable ambulance lifting table used for receiving thereon a stretcher and adapted to be selectively switched to a cushioned mode of operation, said hydraulic system comprising a cylinder for actuating the lifting table, a hydraulic accumulator for cushioning the lifting table, a pump, a three-way valve, and a discharge valve means connected to a reservoir on the outlet side thereof.
DESCRIPTION OF THE PRIOR ART
It has been known for a fairly long time to hydraulically actuate hydraulically the lifting table which is used for receiving thereon a stretcher in an ambulance. The hydraulic system for hydraulically actuating the lifting table must fulfill a plurality of requirements so as to permit treatment of a patient at a so-called shock position, at which the table is secured in position at its top or bottom dead centre, within the ambulance, or so as to obtain a cushioned support of the table at a central position of the cylinder. The requirements which have to be fulfilled by such a hydraulic system include, as will be shown by the explanations following hereinbelow, also strict safety specifications which are intended to prevent the patient from being harmed even if the hydraulic system for the hydraulic actuation of the lifting table is actuated incorrectly.
In the known hydraulic system of the type mentioned at the beginning, the hydraulic accumulator is connected directly to the cylinder and can be blocked by a pressure-independent 2/2-way valve. This known hydraulic system can be operated incorrectly in different ways or it may happen that technical defects occur, which may cause danger to the patient and the medical personnel in the ambulance. It is, for example, imaginable that the patient who first lies on the stretcher is very heavy and that, when the patient has been moved, the lifting table is lowered down to its bottom dead centre prior to removing the stretcher from the lifting table. If, during this lowering operation, the residual pressure is not fully discharged because of a technical defect, e.g. because of an electrical disconnection, a high pressure corresponding to the heavy weight of said patient will still prevail in the hydraulic accumulator. If the next patient who is placed on the lifting table on a stretcher is not heavy and if the fluid connection to the lifting cylinder is opened by pressing the "lift" button, the high pressure, which is still stored in the hydraulic accumulator, will cause the lifting table to move abruptly upwards. It need not be explained in detail that, especially in the case of patients with back injuries, jerky operations of the lifting table must not be permitted under any circumstances. For eliminating this kind of problem, it has already been suggested to provide the hydraulic accumulator with a manometer so that the ambulance attendant or some other operator can recognize a dangerous high pressure in the hydraulic accumulator. Taking into account the hectic kind of daily work which has to be done by emergency medical personnel when they are on duty, it cannot be expected that the emergency medical personnel will actually check the manometer display prior to each actuation of the lifting table.
A dangerous pressure difference between the hydraulic accumulator and the lifting cylinder will also be generated if a patient or an operator leaves the table in the blocked condition of the cushioning system. If some type of adjusting knob is now actuated, the table will inevitably move upwards abruptly. This movement can be so violent that acute danger may even be caused to persons who stand or sit in the vicinity of the table and who touch the table with a part of their body. If, due to a technical defect, the table is discharged by a hand-operated emergency discharge valve, it depends on the operator how long he main
REFERENCES:
patent: 4078269 (1978-03-01), Weipert
LandOfFree
Hydraulic system for hydraulically actuating an ambulance liftin does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic system for hydraulically actuating an ambulance liftin, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic system for hydraulically actuating an ambulance liftin will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-192948