Is there only one hose coming off of the cylinder? If so, then you have a single acting cylinder. Pressure on the "up" stroke; gravity/weight of box/bed on the "down" stroke. If you use a newer tractor on these older cylinders, just becareful not to apply extra pressure when they are at their upper end of their stroke, better yet is too never quite go to the maximum end of its stroke to empty the wagon(thus no excessive pressure). My Dad has many of these types of single-acting cylinders on old dump wagons and we use newer tractors to operate those cylinders, BUT we always try to stop short of full/max stroke. Never had a problem.
Note: It helps to shutoff the tractor on the downstroke and the hydrualic fluid returns to the tractor quicker(gravity down).
If it has two hoses going to one hyd. cylinder than it would be double-acting cylinder. On my dad's older portable JD
green hyd. double-acting cylinder, the JD mechanic says that it
can't handle the pressures of the newer tractors. You must purchase one of the JD
Black hyd. portable cylinders($700) to handle the newer tractors. Portable hyd. double-acting cylinders where commonly used on older farm equipment. They would be transfered from pull-behind disc, chisel plow, culti-mulcher, grain drill, rear blade for tilt/angle, etc. The farmer would only need one cylinder. Today's equipment basically all come with their own cylinders as part of the equipment.
