At a coal mine where I ran the shop we had three D550B articulated haul trucks that used three stage shot gun cylinders to lift the boxes. The pistons were captured with a large nut and the nut was drilled and two set screws were screwed in, one to upset the threads on the rod and another on top to prevent the bottom one from coming loose. All three trucks had the pistons come loose and send trash into the hydraulic systems. The box lift and steering systems were separated by a shuttle valve, one of Cat's supposed ball resolvers. The trash went from the cylinders, hit that shuttle valve and joined the steering system directly to the return to the reservoir. First truck it happened to was driving a high bank in third gear and suddenly turned to the right and dove off the bank and nearly ended itself and possibly the driver down a very high wall.
Later on while I was employed by the Cat dealer in my area, Cat decided to employ that idea again for excavators and some dozers putting a linear encoder inside the cylinders. The same thing happened again and the cylinder shop was swamped with warranty claims.
I'm not a fan of spiking threads to hold a piston rod nut on. I've had a mechanical engineer tell me on the truck catastrophe that a properly designed threaded retainer will not come loose when the proper amount of torque is applied at assembly. Doing the Sherlock thinking, if a nut or bolt comes loose in operation it wasn't assembled properly or the design was faulty. Going further then, the use of extra procedures to ensure a nut or bolt doesn't come loose is either meant as a feel good procedure for a bad design or the idea that someone in the field does not have the capability to follow the correct procedure of assembly. I've used lots of red and blue Locktite for years knowing it most likely was making me feel better about my reassembly. I haven't spiked a thread since I was apprentice almost fifty years ago.
