Repair of 2spd PTO unit

This repair info pertains to the removed PTO unit. Use this info to replace shafts ,brakes or clutches within the unit. Start by removing the 4 3/8" bolts that attach the pump housing to the unit. The pump housing is bell shaped 7 1/2" in diameter. You may need to jar it loose with a soft faced hammer. Set unit aside ,usually no further disassembly is necessary for the pump.The large snap ring holding the clutch PAC can now be removed along with the clutch PAC. If the clutch PAC is to be replaced no further dissassembly is required. To continue dissasembly ,the large spring in the center of the clutch carrier needs to be compressed enough to remove the snap ring. This may be done in a press or by making a simple tool. I will explain how to make the tool in another post. Be careful removing this spring , it should expand to at least 5" in length if it is to be used again. With spring removed ,remove snap ring above clutch piston.This snap ring is a stop for the clutch piston so it cannot over stroke if the clutch PAC becomes too worn.Thread in 2 1/4" X 4"+or_ bolts into the threaded holes in the top of the clutch piston. By use of the 2 bolts as handles pull up with a twisting action to remove the piston. Inspect the outer lip seal and inner Oring seal on the piston for wear, nicks or heat damage.These seals should be replaced and are included in the seal and gasket sets I use and sell.With piston removed the next step is to compress the brake piston springs that are pushing the clutch carrier up against the snap ring inside the carrier. You can either use a press again or the same tool that was made earlier. Basically you need to push the carrier drum down enough to remove the snap ring. With the snap ring removed ,the clutch carrier drum can be pulled up off the splines of the 1000 rpm shaft. The 2 Teflon seal rings on the drum can be replaced at this time. If they look good( no sign of wear ,nicks or cuts) I leave the old ones in place.Installing new ones is a procedure in itself.The new ones need to be warmed up in hot water ,stretched, installed and re compressed. With the drum removed ,the remaining 2 bolts holding the rear cover to the valve housing of the unit can now be removed. The spring pressure of the 3 brake piston springs will push the cover away from the unit valve body as you loosen the 2 remaining bolts. There are 2 dowel pins that may hang up the separation process. Lift off the valve body . Inspect the 3 brake pistons. There should be at least 3/32" of brake pad material remaining on the end of the pistons ,if not they should be replaced. At this point the the idler gear and it`s 2 thrust washers can be removed and set aside. Now removal of either of the 2 shafts ,bearings and seals will be self evident.Any questions or comments? I will go through the assembly procedure in another post. JLS

This information pertains to the PTO unit of IH tractor models 706-1586. The PTO unit on these tractors is a self contained assembly bolted to the rear frame of the tractor. The power is transferred to the unit by a constant running shaft driven by the clutch pressure plate. The constant running shaft powers a hydraulic pump driven by the input shaft of the PTO unit. ( this pump is self contained in the unit and only supplies pressure to the pto unit)The hydraulic pump supplies oil pressure to a control valve inside the PTO unit housing. When this valve is activated , it directs oil pressure from the pump to a hydraulic piston that when pressurized engages a clutch pac which drives the out put shaft.This unit can be removed from the rear frame of the tractor for repair. The complete unit needs to be removed,it cannot be disassembled on the tractor. Removal requires draining the transmission/rear housing oil. Removing the 3PT hitch upper link bracket/cover allows access to aid in shaft alignment.The unit can be pulled back enough to disengage the drive shaft ,care should be taken to not damage the oil sump tube which angles down towards the bottom of the rear frame housing. The complete unit can be removed from the tractor for repair. Using 2 of the long bolts that held the unit in the tractor ,screw them into the 2 top rear threaded bolt holes( they will be sticking out the back while unit is still in the tractor) . They will act as legs to stand the removed unit on them and the 540 output shaft. The input shaft will be pointed straight up. Now it will be easier to repair the unit. JLS