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Topic: Air brakes wont release /trans wont move from neutral (Read 1440 times) previous topic - next topic

Re: Air brakes wont release /trans wont move from neutral

Reply #25 –
use a known good air pressure gauge and attach it to one of the drain valves on your tanks, use this to check air pressure when running engine, am thinking should be 120 plus or minus, it takes that to release the spring or Maxie Parking brakes. the 120 appox is important if you only are getting 75 you have a problem and call a mechanic
1988  40' Grand Villa Cat 3208t

Re: Air brakes wont release /trans wont move from neutral

Reply #26 –
The operating pressure constantly cycles between about 90 psi to 120 psi. The spring/maxi brake button will pop out (or in depending on the brand) and the spring brake will be applied when the pressure drops into the 40 to 60 psi range. If starting up from zero pressure, the parking brake will not be able to be released until the pressure builds to approx. 60 psi. Even when it is released, the coach will not necessarily be at ride height until the pressure is up in the normal operating range.

Pierce

Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Air brakes wont release /trans wont move from neutral

Reply #27 –
Quote from: Old Toolmaker –
So I just gotta ask, and it's something you would do without thinking:  Is there a brake interlock?  As in: Do you need to apply the service brake before shifting?
Nope, sometime I will have parking brake off, and put in gear with no foot on brake 
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Air brakes wont release /trans wont move from neutral

Reply #28 –
The parking brake is released via a 1/4" air line running from the parking brake valve on the dash to the parking brake relay valve located on the "ceiling" behind the rear bulkhead, in the rear axle area of the coach. When the parking valve is pushed in air is sent to the relay valve which shifts and sends air to the emergency/parking side of the brake chambers, overcoming the spring pressure and thus releasing the parking brakes. (providing sufficient pressure is present)

I know of an incident where a rodent had chewed into this 1/4" air line where it exits/enters the bulkhead and not enough air pressure was available to shift the relay valve......might listen for an air leak back there with the parking valve pushed in.

You could always cage the brake chambers so it could be moved or even driven....but beware you won't have any parking brakes, have chocks and another person handy. It could be moved or driven providing you can get the transmission engaged, but at least you'll have the parking brakes released.
Ralph
96 U270

Re: Air brakes wont release /trans wont move from neutral

Reply #29 –
Quote from: turbojack –
Nope, sometime I will have parking brake off, and put in gear with no foot on brake 

Thank you for the information Turbojack, I guess that takes that line of inquiry off the table.

As nice as is the 6-speed Allison, I'll keep working within the limitations of my Allison version of the Hydramatic.  I have a couple of decades experience driving Cadillac limousines, first a '49 and later a '59, so early and later generation Hydramatic transmissions and my Allison 4-speed with dual lock-up feels pretty much the same.

Tonka should ask the collective how to access the fault codes with his key pad.The U270 is too heavy to push back and forth to try and get the transmission to pop into or out of gear.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Air brakes wont release /trans wont move from neutral

Reply #30 –
Quote from: Old Toolmaker –

Tonka should ask the collective how to access the fault codes with his key pad.The U270 is too heavy to push back and forth to try and get the transmission to pop into or out of gear.

In his first post, Tonka said he checked and no codes.  If he did it with the up and down arrows, then it checks out.  If not, indeed ask, as the procedure is simple and done from the driver's seat.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air brakes wont release /trans wont move from neutral

Reply #31 –
So the GODS have spoken and the trans/brake problem is fixed !!!Thank you all for the help. Only problem is I don"t really know what I fixed . I removed shift panel from (armrest) and looked for problems there. Panel looks like it had been removed/worked on before taped connections and 2 cutoff orange wires ?  Tried to remove and clean connections but stopped short of pulling off plug (it did not want to cooperate) so I gave it a try and wallah bata bata bingo it worked. Not sure I had a brake problem or not, maybe trans was just hung up. So to my next Question is trans shift pad part # 29507949  Model #REM0002 SN # 2179904 is this a WTEC 1,2,or 3. I think this might be suspect  also  as it has acted funny before so I want to replace if not too many Bill Bucks lol. Trans is a allison  MD3060R  ( 6 spd with retarder ) Thanks and Thanks again for all the valuable help this forum provides ,,,  TONKA
What a long strange trip it's been

Re: Air brakes wont release /trans wont move from neutral

Reply #32 –
And, still no Allison codes through all of this??
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air brakes wont release /trans wont move from neutral

Reply #33 –
AS far as I know NO codes. I pressed down on up/down arrows and got a response of d-1 d-2 d-3 d-4 d-5 but no codes. Did I miss an additional step ?
What a long strange trip it's been

Re: Air brakes wont release /trans wont move from neutral

Reply #34 –
Quote from: tonka –
So to my next Question is trans shift pad part # 29507949  Model #REM0002 SN # 2179904 is this a WTEC 1,2,or 3.
Check the Transmission Instruments web page.  John Kopalek is the Allison Guru.  They have some tech info on the different WTEC versions.

Transmission Instruments


1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air brakes wont release /trans wont move from neutral

Reply #35 –
If you got d-1 - -, there are no codes.

You would have to push the mode button to go from d-1 to d-2.  If it progressed through the codes by itself, something "ain't rite"-- call John!
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020
 

Re: Air brakes wont release /trans wont move from neutral

Reply #36 –
The orange wires are supposed to be cut on our coaches, if connected it is used for a remote touchpad that some trucks may use.

Probably should unplug and reconnect the cable to the keypad to make sure it is seated all the way.

John Kopalek can rebuild them much cheaper than you can source one, It will scare you what they cost. Hope your condition was just a fluke and if it happens again you should give John a call at Transmission Instruments. Nice guy and may be able to help you trouble shoot this problem over the phone.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota