View Full Version : Toro 322D PTO Slipping Issues
05-18-2010, 01:56 PM
Our 322D fitted with 72" 3-blade mowing deck has been causing its double-width "Torque Team" engine-to-PTO drive belt to slip when trying to mow heavy grass. Inspection revealed that those two pulleys had become misaligned by the PTO shaft moving forward about 0.5 inch. So we will execute the PTO shaft forward-aft repositioning procedure to realign the tops of those pulleys as the pulling side between the tops of the pulleys. That procedure calls for loosening a set screw on the forward and rear PTO collar, then driving a flat-end punch with a hammer to spin those collars in the opposite direction of the machine's normal operational spin direction. That reportedly loosens their grip on the PTO shaft, allowing it to slide to the correctly adjusted position, then retighten by driving in the opposite direction with the hammer & punch and finally tighening the set screws.
Question, is the gripping that spinning these collars causes onto the PTO shaft like that of a drill chuck or an over-sized Dremel Mototool collet? The gripping mechanism is concealed so its method of gripping is not apparent. Clearly the gripping is not mainly held by those tiny Allen head cap screws.
When the operator pushes the PTO control lever forward, it induces a twisting force on the floating PTO assembly. That twisting force is resisted by two links. The Torque Team belt length limits that spring-loaded twisting. Also, the yoke link between the spinning engine drive shaft and the which PTO assembly resists that spring-loading force. During partial disassembly for inspection, we discovered that the pin which links the smaller end of the yoke to the PTO assembly has worn the originally-round hole in the PTO assembly into an oval slot. It was not fitted with a grease zerk yet it obviously is a wearing loaded mechanical connection. This slot verses the original round hole slightly changes the geometry of this spring-loaded system.
Question 2. Does this geometry change decrease, increase or not change how effectively PTO belt tension is controlled by this complex spring-loaded pivoting linkage system?
Thanks for your consideration. I do own and have studied the original 3-ring binder Shop Manual.
The Toro Company
05-21-2010, 11:11 AM
1). The bearing retaining system is known as a cam-lock collar system. The collar is off set, something similar to a cam shaft lobe. When it is rotated, it will bind of lock to the shaft. The set-screw then only needs minimal retention properties because the force of the cam action against the shaft rotation does most of the work. This is why you need to rotate the collar to remove.
2). Short answer is that the wear in the pin/yoke will decrease the belt tension. To what level depends on the wear. However, keep in mind that the lever spring-loaded over-centering action can compensate for some of the wear.
Toro Commercial Service
05-27-2010, 11:34 AM
Thanks for your reply Eric. On closer inspection, the non-greased wearing surfaces against the bolt which fastens the yoke's small end to the PTO assembly wore the originally round holes in both the PTO arm and the yoke into ovals. Added together, their extra clearance probably only decreases the effective yoke center-to-center length by about 1/4 inch. You're right, the spring adjustment system can take care of that. But on reassembly, I will apply grease to that fastening bolt. Its heavily-loaded sides are definitely a wearing surface as is reflected by how that bolt wore into both the yoke and the PTO assembly arm.
Now I am compelled to speak of that front cam lock ring. Trust me, you do NOT want to deal with a PTO shaft that refuses to slide yet is holding the pulley about 5/8 inch out of alignment compared to the engine pulley. I've jacked it up in the air 4 times now to work on that problem. Following the Shop Manual instructions, I used a punch and hammer trying to spin the cam-locking rings in the opposite direction from the shaft's normal travel. First I used a 16 ounce hammer, then an 18, then a 20 ounce. Next I went to a 3-pound short-handle mall. Then I used 140 pounds per square inch air pressure to drive my hand-held air hammer fitted with a small blunt tip into the hole trying to get the front ring to spin. The rear one loosened nicely. Next I used my acetylene torch to get that ring hot. It is within 2 inches of an easily degraded high-pressure hydraulic hose, which I covered with a wet cloth to prevent burning that hose. Grease from the grease-zerk-lubricated bearing there began burning and dripped onto my face. Horrible experience. More hammering while hot and it still didn't unlock. I've applied a "come-a-long" cable puller to the center of the 3-spoke PTO pulley pulling toward the machine's rear and applied C-clamps pulling that cast iron pulley toward the cross-member frame there, worried that I might break that casting, then pried and hammered at every available point on the shaft toward the rear. It has not slid yet. I formed a tool from a 1 inch-internal-diameter pipe section, cutting away an angled section toward one end to allow me to apply blows to the step ring in the PTO shaft just behind the front universal joint while the C-clamps and "cable pull" tools were pulling the shaft rearward. I used my 3-pound hand mall. This is very awkward work and leaves my knees black and blue from breaking blood vessels. That xyz-designed cam-lock ring has bested my attempts to spin it to loosen the PTO shaft so the shaft can be slid back to align the pulleys.
Since it's gripping so tightly, I don't see how it could have let the shaft slide forward what I'd estimate to be about 5/8 of an inch causing belt misalignment.
I now suspect that the Chicago Parks Department, which sold this machine to me, did so because their mechanics had been unable to adjust this PTO pulley alignment problem. I now know that it was eating Torque Team belts when I bought it from them but had a fresh belt installed. The Parks Department employee who helped me load the mower onto my trailer said that it may need a new belt soon. Within 10 running hours of installing new belts, it starts slipping again. I suspect that they sold this problem machine to get rid of the problem. I later discovered that the hole in the front cam-lock ring, into which the manual suggests hammering with a punch to spin the ring, was quite distorted, but only toward the side used to attempt loosening. Someone had tried to loosen that before I even knew these cam-lock rings existed in these machines.
I'm pretty frustrated, bruised and tired from trying without success to fix this vexing problem. As to why Toro designers did not provide a much better tool perch to grip onto those cam-lock rings for spinning, I don't know. Obviously I feel they could have done better without significantly increasing that part's production cost.
I'm open to suggestions. Many spring-loaded self-closing hinges include a spring preload-adjusting ring with holes drilled into its outer diameter. Those hinges are sold with an installation tool which wraps part of a rotation around that ring, terminating with a catch-paw which locks into any of those perimeter holes. I'm now considering buying a large box end wrench sized large enough to wrap around that stuck cam-lock adjuster ring. Then cut away most of that wrench's box ring so it can slip over the shaft and fit part way around the stuck ring. If I drill and tap a hole through the side of the box wrench ring, perhaps I can make a catch-paw tool to grip onto the outside of that amazingly tight adjuster ring. So I would be making an over-sized copy of those hinge adjuster ring tools. Any better suggestions? "Help, help, I'm caught in the kelp." I need for this mower to be mowing.
Any ideal how many degrees of rotation the cam-lock rings must be rotated to release the shaft?
05-27-2010, 11:00 PM
You may need to drop the whole PTO assembly from the mower. I jack the mower up and set jack stands for front and rear to get good clearance under the tractor. Removing the assembly will give you the access to remove this stubborn lock collar. Also inspect the PTO shaft for wear at the bearing mating area. Inspect the bronze bushings the support and control rods go through as well as the rods themselves for wear. Inspect the bushings at the PTO fork. All these areas wear and add up together to cause slippage. We have 6 322/325D's some with 8K hours + and they are good machines. If you intend on keeping the machine and doing most of your own mechanic work get the service manual it will pay for itself.
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