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Airdirect · 02-09-2019, 11:19 PM

If you have spring parking air brakes (bottom picture), they are the best parking brake to have. Some air parking brakes rely on air pressure to hold them on and will release once air pressure leaks off. I had a 1968 GMC 9500 that did not have spring parking brakes, just the lever transmission drum brake. It was a poor setup as you would set the air parking brake and the drum, then the air would leak off and the truck could overpower the manual brake and roll.

02-09-2019, 11:19 PM	#104
Airdirect Registered User Join Date: Oct 2016 Location: Powderly Texas Posts: 300	Re: 69 c50 If you have spring parking air brakes (bottom picture), they are the best parking brake to have. Some air parking brakes rely on air pressure to hold them on and will release once air pressure leaks off. I had a 1968 GMC 9500 that did not have spring parking brakes, just the lever transmission drum brake. It was a poor setup as you would set the air parking brake and the drum, then the air would leak off and the truck could overpower the manual brake and roll.