Ritter 75 evolution

First thing get the model and serial number off of the back (behind where the pt. right shoulder would be). Next figure out where the oil is coming from: start with what you see and work your way up until you don't see anymore. This table has 4 cylinders and the shaft of each should be dry, as evidenced by a white felt ring where the shaft exits the cylinder. The best way to check this is to raise all of the cylinders to full extension: back, base, tilt and table all full up. If it makes a "grinding" noise then there is air getting mixed into the reservoir due to low fluid. It is essential to use only the correct fluid as recommended by the Mfg. and follow their instructions for filling. Also, be aware that, if the table has experienced any unwanted motion: i.e. any function drifts down after being placed up, that the reservoir will overflow thru the vented cap and this could be your source of oil. If it is not a cylinder then it is usually a hose or fitting. Midmark has all the manuals at their web site. Good luck.

The first thing you will need to know about this chair is the complete model description and the complete serial number - Midmark/Ritter uses a base model number with a three digit suffix and a serial number with a two character prefix - this should be located on a Serial number plate often located underneath the chair back.

Once you have the complete model description and serial number you should look at the Evolution 75 Cross Reference I have added to the Med-Wrench Evolution 75 page under the Resources heading - this will tell you which Service Manual you will need to use in finding the leak. You can find the Service Manual for these chairs here on Medwrench or on Midmark's web site (www.midmark.com) where they can be downloaded free of charge.

Once you have the manual in hand it will tell you how to remove the lower covers (no specialized tools or bracing needed) so you can gain access to the various hydraulic cylinders and hoses where it should be easy to identify the damaged components.

Unfortunately since these components use flair fitting there are no recommended sealants or tapes you can use to seal the leak - you will have to replace the damaged components to repair the leak. When working on the chair be sure to read and follow any safety procedures mentioned in the repair section of the service manual. Be very careful about the routing of the replacement hoses to avoid crimping or abrading the exterior of the hose. Avoid over tightening these fittings as they are damaged very easily and can strip out the threads in the cylinders which can not be repaired.

You should also refill the pump reservoir (procedure is in the manual) with 100N Mineral Oil to avoid running the pump dry as this can very quickly damage the internal pump seals.

RPI has the parts and hydraulic fluid you will need for this repair and if you have any further questions feel free to call me at 800-221-9723 Ext. 135 from 8:30 to 4:00 PST.