Shock Absorbers

[eatonaxle]

Hi Folks.
I have 2 questions on Houdaille Shock absorbers.
Question 1.
At the bottom of the rotor in the round section of the rotor, there are 2 holes through the rotor at right angles to the shaft. One hole is controlled by the needle valve for resistance adjustment, what is the other lower hole for?
Question 2.
In the inner chamber,(the part with the 1 1/2" nut) there are 2 or sometimes 4 small plugs. What do you think they are for? I think I know for sure, but I would like to hear other angles on these plugs.

 

[TomW]

According to some info I have on Houdailles (that I don't know the source of):

1.The X-pattern holes in the rotor equalize pressures on both wings to reduce bearing wear.
2.The "bleed plugs" in inner cover vent air and gas-off from the inner chambers, and may serve as pressure-relief valves. They are called "nut bushing plugs", and have a very small groove running along their length so as to permit air or shock fluid to pass through.

 

[Blessyouboys]

There is a lot of good information on houdaille shock absorber construction and rebuilding available here.

 

[Bill Stipe]

The plugs in the inner cover are both vents and replenishing valves the top ones as the shock is mounted would be vents on both sides of the dividing chamber wall bleeding air out of both sides the lower one is for replenishing oil in the chamber I have only seen 1 of these per cover but some could have 2 I don’t think it would matter or the design is totally different but the end function will be the same?

I design my shocks a little different only because the original design is even more labor intense to machine and build.

I will describe the function a little different then some units are made the end result is the same and it may shed some light on how the shock functions.

The way the Houdaille model A shock works on say the CW unit. The wing shaft has 2 cross holes drills 1 below the needle valve and 1 above the needle valve as the wing shaft rotates cw the upper or top check ball in the chamber dividing wall closes an orifice hole forcing the all the oil through the needle valve and a little out the vent hole plugs along with any air. At the same time the lower check ball in the chamber dividing wall opens drawing in any fluid that may need replenishing from loss through the vents. As the oil passes the needle valve it exits above the needle valve cross hole flowing to both sides of the wing shaft voids as it does entering the needle valve from both sides also. This would be the rebound side of the axle slowing it down base on your adjustment and help prevent the spring mounts from ripping off the front cross member. As your car plunges back into a pot hole the wing shaft reverses and rotate ccw and the upper check ball now opens and oil flows through an orifice hole doing its metering and the lower check ball closes preventing oil from flowing back into the reservoir some oil will flow backwards through the needle valve also but the ccw movement gives you a much softer action to produce a 60/40 action more or less depending on the oil viscosity.
I hope I did not miss any thing.
With that said if you look over the plugs and drilled holes you should be able to visualize what each thing does.

Bill Stipe

 

[mot]

Bill has explained it really good
here are the two vent plugs
they are staked (with a chisel,to keep them from being forced out under pressure) they have a thin groove lengthwise from inside to outside the cover
this is what allows the air to vent and let the oil in from the lower ball check valve,
i use a razor knife to clean out the groove,and a 22 caliber rifle wire bore cleaner to clean out the hole in the cover
i just rebuilt 50 shocks and only found two plugs per cover ,
i know others have found from 4 to 6 plugs
Reading rebuilding articles one said to put all CW shocks in one barrel and all the ACW shocks in another barrel, big mistake
they are a matched set
each cover is drilled to have the plugs at the top and on either side of the stationary vane,notice the punch mark between the two vents?that is to align the cover with a similar punch mark on the base and moving vane
when the cover is snugged up that dot will be in the correct position
if parts from different shocks are mixed ,the vents will be in the wrong position,so the rebuilder had to drill new holes and put new plugs in
another point
there are two different size nuts,one is 1 1/2 and the other is 1 9/16
plus some of the late 31s have a three rib design ,no nut
tom