Are Type 20 Brake Chambers Normal on an '88 378?

Hey I'm trying to start new thread and can't figure out how. How did you start yours

 

It should have 30’s on the rear axle and 24’s on the steers. The front drive will be only one with 30/30 or park brakes

 

That’s a type 30. 30/30 references the park and service diaphragm size. Type 30 is a single 30 square inch service chamber. Type 20 is likely on the steer axle. And yes it was common to only have one parking axle.

 

I had a 1998 FRTL 132 XL (Classic) that had no parking brake chambers on a rear axle. One time the truck started to move after setting the brakes on a hill and weighing 80k+ lb (probably 85-90k of bulk potatoes, lol). That's when I figured it was time for new brake chambers

 

Was that an older truck thing or is it still common having spring brakes on only one drive axle?

Just curious, never seen it before.

 

Most new trucks come with parking brakes on both axles. I don’t think there is any law, just that’s how they are spec’d now

 

Depending on make of truck and suspension spec’d as to what axle they were on. Pete air rides they were on front drive. KW air rides they were on rear drive. I’ve seen FL’s either way. Having 30/30’s on both axles was an option. Pete used to call it the full Ankorlock option on the sales orders in the late 60’s and 70’s. MGM/Ankorlock was the oem supplier to paccar back then. 100% servicable All aluminum body chambers.