Thursday, February 16, 2017

General Electrodynamics scale rehab

I bought a set of aircraft scales to use for the GMC or what ever else. The set had two 5,000 lb scales and one 2,000 lb. Only one worked. Replaced two of the handle springs with a cut down Ebay spring.
     To get them apart there are snap rings and discs that cover two socket head fasteners on the bottom which hold the top on.
These scales operate like a bathroom scale where levers press on the measuring part. These are hydraulic using a gage and a piston that the levers press on.
The brass screw is where the oil is put in. Two of these had o rings that failed and needed oil. At first I used oil that was too high in viscosity and the gages moved real slow. Drained that and put in thinner oil and it worked ok. Doesn't take much oil.
The black part is a diaphragm which the piston presses on. There was rust stuck on the diaphragm which came off with a vinegar soak and neutralized with baking soda.
                                          Levers and top cleaned up
                  Two broken screws, one came out other not.
They did put steel inserts in the aluminium and that did come out.
               Cleaned, greased and ready to reassemble
      Stacked for testing, match pretty close 500, 750, 1000, 1500 and 2000 lbs
  Testing the 5,000 scales to see if they match

Monday, January 9, 2017

Black tank done

Lid attached to tank flange with Gflex and then two layers of 9 OZ over the edges
           3/8 x 4 aluminium straps to hold it in


Mounting straps made of aluminium and twisted to conform to the tank bottom
Valve and sender mounted. Valve is Valterra pattern
Leak test, it took 309 lbs of water before it quit venting.
Oring slip fitting for shower and lav, 3" for toilet and depression for shower trap
1-1/2 bung for kitchen

Sunday, December 25, 2016

Tank bungs and lid reinforcement

Used West System Gflex epoxy to install the tank bungs
Gflex is tough stuff and looks like it will be more than enough to hold bungs.
Here is a video of a Kayak sawed in half and stuck back together with Gflex
                             Ribs on inside of lid to stiffen it up.
  Added a couple vents to the marine plywood core so it can dry out if it ever gets wet.
                                Test fit of the top and bottom

Monday, November 28, 2016

Saginaw steering pump pressure relief modification, now 1,600 psi brake pressure

With Hydroboost brakes more steering pressure equals more brake line pressure. PSC sells a new Saginaw P style pump made by Delphi which is supposed to be set for 1,650 psi.
http://www.pscmotorsports.com
After installing it I found it didn't quite make the pressure spec. I'm shooting for 1,650 psi pump pressure by making a new flow valve plug with a 20% smaller area seat for the relief valve ball. The thread on the plug is 3/8-24 so I started with bolts of like thread and went from there.
 Had six flow valves to fiddle with!
Springs and balls were the same on all. There were two different lengths of valves and corresponding plugs. The orifices and seats were the same on all. Had a few shims to work with too.
Had four bolts to use and they needed the hex changed to 7/16" from 9/16"
Made a fixture to hold plugs for machining. Here is a screen ready to go in.
New plug, original plug with screen removed and original plug unmolested.
Made orifice .052" closest I had to .050" original
New plug with 20% less seat area.
Rolling screen in.
Screen rolled in new plug and original plug
Valve ready to test
 where screen goes
With no shim the spring is very close to coil bind so I didn't pursue shimming the spring. No shims on the valve is about 1,400 psi.
 After some more fiddling we got 1,650 psi from the Saginaw pump. Ended up shortening the end of the flow valve where the plug screws in .015"

rear brake pressure 40mm master 80mm front and mid, 66 mm rear calipers
front brake pressure 40mm master 80mm front and mid, 66 mm rear calipers
There is some concern running the steering box at a higher pressure than It really needs. To lower the pressure just to the box I put in an additional relief valve before the box. Sun Hydraulics has all this stuff.
              I selected a AEJ manifold in steel
           The relief cartridge I selected was an RDBALAN
                    Ready to install with Oring boss adapter fittings
To install I got a 20 inch hydraulic hose to go from the hydroboost outlet to the manifold and used Bob Stones kit original hose from the manifold to the steering box. Bob's hose clocked OK to hook up this way. The return tees in before the cooler. I set the pressure to be just enough to turn the wheels while stopped.