A blast from the past.
in [Technical]
|
Prev: 2000 Mazda Protege blue smoke at startup. Why?
Next: Q RE: GM 4x4 "wax motors" and when they were replaced with somethingbetter...
From: TomO on 27 Apr 2007 15:52 I have a need to get an old 1951 GMC 2.5 ton side-dump farm truck running for a few errands. This truck has been parked out behind the barn for about two years now. My question is about a part in the brake hydraulics system. When I started the project, there was no brake pressure. A several minute search brought me to the master cylinder that is located under the driver's position floorboard. Pulled a plug from the floor and found where the reservior is (it is actually the body of the master cylinder itself). Following the hydraulic line from the master cylinder brings me to the part in question. This is a large cylindrical device about six inches in diameter with a narrower neck coming off the front of it. The neck feeds into a rubber tube that ends at a breather of some sort mounted on the firewall. There is a bleeder for the brake system in the narrow neck as well, and the brake lines come off of there too. There is also a feed from this device to the hydraulic pump for the dump bed on this truck, but I don't believe that the system shares the fluid between the brakes and the dump hydraulics. I got the brakes working well, but I'm still baffled by the purpose of this rather large device in the middle of the system. Any ideas? -- TomO
From: TomO on 27 Apr 2007 16:08 TomO wrote: > I have a need to get an old 1951 GMC 2.5 ton side-dump farm truck > running for a few errands. This truck has been parked out behind the > barn for about two years now. > > My question is about a part in the brake hydraulics system. When I > started the project, there was no brake pressure. A several minute > search brought me to the master cylinder that is located under the > driver's position floorboard. Pulled a plug from the floor and found > where the reservior is (it is actually the body of the master cylinder > itself). > > Following the hydraulic line from the master cylinder brings me to the > part in question. This is a large cylindrical device about six inches in > diameter with a narrower neck coming off the front of it. The neck feeds > into a rubber tube that ends at a breather of some sort mounted on the > firewall. There is a bleeder for the brake system in the narrow neck as > well, and the brake lines come off of there too. > > There is also a feed from this device to the hydraulic pump for the dump > bed on this truck, but I don't believe that the system shares the fluid > between the brakes and the dump hydraulics. > > I got the brakes working well, but I'm still baffled by the purpose of > this rather large device in the middle of the system. > > Any ideas? > OK, bad form replying to my own post. I know. Thinking about it, could it a system that is set up to apply pressure to the brakes while the dump bed is in the up or tilted position? Was there such a thing on these old farm trucks? -- TomO
From: cuhulin on 28 Apr 2007 18:14 Sounds like it is a brake booster to me.Look them up on the net. cuhulin
From: TomO on 29 Apr 2007 07:33 On Sat, 28 Apr 2007 17:14:08 -0500, cuhulin wrote: > Sounds like it is a brake booster to me.Look them up on the net. > cuhulin No vacuum lines to it though. My Google searches have been fruitless so far. Have you got any search terms that may find this part? I've tried 1951 GMC farm truck brake systems and a few other variants. No luck for me yet. I think it is not a booster, but who knows? I've been wrong before.
From: Dan_Thomas_nospam on 29 Apr 2007 22:16
On Apr 29, 1:33 pm, Ashton Crusher <d...(a)moore.net> wrote: > On Fri, 27 Apr 2007 14:08:00 -0600, TomO <tom@_nospam_towens.com> > wrote: > > > > > > >TomO wrote: > >> I have a need to get an old 1951 GMC 2.5 ton side-dump farm truck > >> running for a few errands. This truck has been parked out behind the > >> barn for about two years now. > > >> My question is about a part in the brake hydraulics system. When I > >> started the project, there was no brake pressure. A several minute > >> search brought me to the master cylinder that is located under the > >> driver's position floorboard. Pulled a plug from the floor and found > >> where the reservior is (it is actually the body of the master cylinder > >> itself). > > >> Following the hydraulic line from the master cylinder brings me to the > >> part in question. This is a large cylindrical device about six inches in > >> diameter with a narrower neck coming off the front of it. The neck feeds > >> into a rubber tube that ends at a breather of some sort mounted on the > >> firewall. There is a bleeder for the brake system in the narrow neck as > >> well, and the brake lines come off of there too. > > >> There is also a feed from this device to the hydraulic pump for the dump > >> bed on this truck, but I don't believe that the system shares the fluid > >> between the brakes and the dump hydraulics. > > >> I got the brakes working well, but I'm still baffled by the purpose of > >> this rather large device in the middle of the system. > > >> Any ideas? > > >OK, bad form replying to my own post. I know. > > >Thinking about it, could it a system that is set up to apply pressure to > >the brakes while the dump bed is in the up or tilted position? Was there > >such a thing on these old farm trucks? > > From what you describe taht sounds like a good guess. However, with > rear dumps they often want to be able to crawl them along as the dump > the dirt out so not sure why they would insist that the brakes be > applied unless the truck is just to unstable to move when dumping.- Hide quoted text - > > - Show quoted text - Sounds to me like an early version of Bendix's Hydroboost, which became popular when diesels showed up in smaller vehicles. Diesels have no useable manifold vacuum, so the hydroboost used power-steering pump pressure to boost the brake pressure. The Hydrovac used manifold vacuum to boost the brakes. Dan |