Mico lever lock supplemental parking brake

Somewhat the same system as aircraft parking brakes. When I was airforce and working part time at a service station, I put a T-33 parking brake valve on the tow truck. Worked like a charm for holding the truck when winching.
Art.

All of them that I have ever used have worked great but I wouldn't use it for long term parking. The slightest bit of by-pass will release the brakes.

Ya not for long term parking. I set the park brake plus carry chocks for both truck and trailer. The stock park brake will not hold the truck and a trailer @ 20000 lbs on a 4% sloped pullout. I ended up holding the brakes until the egt cooled enough to shut down the engine and park in gear, then hop out and chock the wheels. The lever lock looks like it might fit the bill.

I worked for a towing company that had them on all the stick shift trucks. They worked awesome. The oem e-brake was never enough to hold the tow truck in place while winching. Most of the older trucks had one line that went to the rear brakes and the mico was installed on the floor in front of the drivers seat or between the seat and the door. All that was required was to tie into the rear line. There was a special adapter kit installed if there were two hydraulic lines going to the rear. It even has a pre-wired circuit to wire to a buzzer or light to indicate low pressure. It was very simple to set oem brake, flip the lever and pump the pedal once and hop out.

They work great. Every corn sheller I saw in Iowa in the 60s had them. Craig

Worked for a company that have one on a roll back tow truck. On day the one office Manger took it home to haul his show car. Well he parked the truck on aND only set the micro lock and not the truck brake e brakes. Well he went on to eat dinner and half an hour later the truck was coasting through his yard and plowed in to his dump truck.
The Micon locks hold good but don't really no them form your only e brake. Also the pa state inspection law says you must have a mechanical parking brake.