Stop tubes are used to reduce the bearing load encountered in long stroke cylinders when the piston rod is extended.
By separating the piston and rod bearing with a stop tube, the life of the bearing cartridge will be increased and the tendency of the rod to buckle will be reduced.
To determine the length of stop tube required, locate the application in the drawings above and calculate “L” from the cylinder “A” dimension with the piston rod extended. For an “L” longer than 40″: one inch of stop is required for every 10″ over 40″ plus one inch for any remainder.
EXAMPLE: An MP1 Rear Clevis Mount Cylinder with Rod Eye, 4″ Bore, 34″ Stroke, 2″ Rod is operating at 500 PSI.
This application matches Fig. 7 (above) and L = A.
L = XC dim. + 2 x stroke + Rod Eye CA dim..
L = 7.5 + [2 x 34] + 3.44= 78.94″
78.94” – 40 = 38.94 = [3 x 10] + 8.94
Therefore a 4″ stop tube is required.
The required length of stop tube should be added to the cylinder stroke when ordering.
The above cylinder example would be ordered as 38″ Gross Stroke.
34″ Working Stroke with 4″ Stop Tube.
This is usually written 38″ [34″]w/4″ Stop Tube.