Air Throttle install

[tomhamrick]

About to install an air throttle on a 6V92 TA. Anyone have pictures of their install so I can see how it looks? Also where did you get the governor mounting plate and lever assembly?
Thanks,
Tom Hamrick

[compedgemarine]

Hey Tom
I just did the same on my 6v92 and needed the same parts. if you go to the williams air throttle site and go to the catalogs there is a page that shows all the parts and the part numbers. after that call
Brake Systems Inc. in portland oregon at 800-452-5734. they buyout all the old stock and over stock from williams and have or can get anything. following are the part numbers and prices of the parts I just got
WM775B-  modulator for HT740 trans     $56.11
119050 mounting bracket                     $22.59
117404  return spring                          $9.17
117908  lever assymbly-long                 $11.86
shipping                                            $11.86
total                                                 $139.62
if I get a chance I will get a photo of mine if it helps. I modified the original plate to mount the shut down solinoid and the one that locks out the throttle on high idle. havent had the chance to start it up yet so hopefully it all works right.
Steve Schmidt
'81 Eagle model 10

[luvrbus]

Tom, mine came from a DD dealer  if you look on Tom Halls site Coach Conversion Central you will see the one I have made for a Detroit also if you need mounting instructions look at    www.utxchange.com   and they will parts also  good luck

[Stan]

When ordering from Williams you have to be very specific on what model engine and if automatic whether you are using an air or cable modulator. I installed one on an Eagle with 692 and 740 with cable modulator but the owner hadn't specified that when he ordered it. It wouldn't come up to full speed and wouldn't shift properly. The cable modulator presents some mechanical load that has to be compensated for with more air pressure. Williams sent me a new spring and shims and instructions on how to set up the treadle valve.  Everything else came with the kit.
On my own 8V71 with a cable modulator I bought a used unit and just made a bracket out of 10 gage plate so that the air pot pushed on the governor lever the same as the original foot pedal rod. In my case, the treadle valve was too much pressure so I put a stronger return spring on the governor lever to make the foot pedal less sensitive.

[luvrbus]

Tom, Stan made my point about the air modulator it is the best way to go 60 bucks is not worth the hassel to me     good luck

[tomhamrick]

You guys are great!!!! Thanks for all the information.
Tom Hamrick

[tomhamrick]

Steve,
A picture would be great if you can get one. My email is tomhamrick at yahoo dot com.

All,
Did any of you use the pressure regulator? If so what type and what pressure?
Thanks Again!
Tom Hamrick

[JackConrad]

Tom,
   We used an adjustable pressure regulator from Northern Tool.  We set ours at 50 PSI.  We found this to be the best setting for us. A lower setting gave us a very "mushy" throttle. A higher setting made the throttle too sensitive (a slight movement of throttle pedal= large increase in engine RPM). We played with our settings for a few short trips to find what was comfortable for us. YMMV  Jack

[Stan]

As Jack pointed out, you are aiming for full stroke of the pedal to give full stroke on the governor. That is Williams reason for different springs and shims in the treadle valve (which is just a bleeder type adjustable pressure regulator). You cannot obtain full stroke on the pedal if you reduce the inlet pressure below the maximum pressure of the treadle valve so you have to adjust it to whatever you are comfortable with. I think varying the return spring tension does more for pedal control than changing the input pressure. At full pedal travel, you can adjust the return spring tension to just allow full governor travel.

[skipn]

   FWIW,

   I tried the spring thing.....wasn't real happy with the results mostly due to 2 things.
     when I was working on the engine it was hard to move the lever to high idle (spring was too stiff for
     my liking)

   With the heavier spring I had to wait longer to press the foot peddle to high RPM. (wait for air pressure to build)
     Being I have a transplant engine it doesn't have a high idle switch.

   I have my regulator set at 55psi seems to work fine and I now have some throttle control at 40 psi at air up time.

  Skip

[JackConrad]

    Here is a photo of the air throttle actuator on the governor and the pressure regulator.  The pressure switch in the air line on the governor is part of the Jake Brake switching circuit.  Jack

[Stan]

skipn: Do you have the regulator feeding the air pot on the engine end? Since I used the original return spring and just used a piece of all thread to make a way to adjust the tension, I am thinking that the output pressure from your treadle must be away higher than required.

To make for easy calculation, if your treadle valve has a maximum output of 110 PSI and you are using a 55 PSI regulator (at either end) then you would only be using one half of the pedal stroke.

[skipn]

The regulator is inline to the feed of the treddle. Before the treddle would go from 0 to 120# with
just the slightest movement of the peddle. With 55# max to the treddle and then  55# to the diaphram max
I can  now feather the throttle. It goes to the high limit without any problems.

   Not saying what I did is the best way but it seems to work ok.


   Thanks
SKip

[Stan]

skipn: It sounds like your treadle valve is acting like an orifice control instead of a regulator. Consider an ordinary valve that you  open 10%, the pressure will rise to the supply pressure, just at a slower rate than if fully open. When you open a regulator 10%, the pressure will only rise to 10% of the maximum for that particular regulator. If the spring in the regulator sets the maximum at 50 PSI then opening the regulator 10% will give you a maximum of 5 PSI out. One type is a flow control and the other type is a pressure control.

I have worked with two different types of air throttles and they both used a bleeder type pressure regulator for the treadle valve. I have been assuming that all throttle treadle valves worked that way but apparently not. Sorry for creating any confusion but I just don't understand how an orifice type valve could be used to maintain a steady speed. According to this catalog page, a Williams treadle valve is a pressure regulating valve with a maximum output of 70 PSI and as I said in a previous post, Williams can supply springs to provide whatever max pressure you want.
http://bepco.biz/AirBrakeCat/148.pdf

[skipn]

  Very true in what you write. The thing that I might inject here is that the treddle goes from 0-70# but depending on
the air throttle cylinder being used it may only require 0-35# as in the link you provided. So at half peddle travel of 70#
  input you get 35# at the throttle cylinder (full throttle). I am not real sure which throttle cylinder I am using but the one thing
  that drove me to irritation was in a 700 mile trip not being able to feather the throttle thus I was either accelarating
  or coasting the whole time. I rode in a bus for 12 hrs once with the driver doing that by the end of the trip I was
  really really cranky (pick a speed and hold it there) He probably had a tired right leg too .

  Springs are probably the correct method but for me I do the best I can with what I know. I will have to research this
  more. Thanks

  Have a wonderful day
  Skip