Special No Override

[stuckmotor]

I ran across the linked presentation on a well preserved JD 60.

You Won't Believe How Original This Classic Tractor Is! John Deere Model 6 - YouTube

3:30 minutes into the video the owner shows a stenciled message saying "SPECIAL NO OVERRIDE". This seemed to have to do with the hydraulics. Does anyone know what the message means? He didn't know and I don't either.

 

[bcp]

Maybe this:

Engineering Essentials: Pressure-Control Valves | Hydraulics & Pneumatics

Cracking pressure and pressure override —The pressure at which a relief valve first opens to allow fluid to flow through is known as cracking pressure. When the valve is bypassing its full rated flow, it is in a state of full-flow pressure. The difference between full-flow and cracking pressure is sometimes known as pressure differential, also known as pressure override.

In some cases, this pressure override is not objectionable. However, it can be a disadvantage if it wastes power (because of the fluid lost through the valve before reaching the maximum setting). This can further permit maximum system pressure to exceed the ratings of other components. (To minimize override, use a pilot-operated relief valve.)


Bruce

 

[stuckmotor]

Sounds good to me, Bruce. Thanks!