Community Forums

Edouard · 10-22-2010, 05:16 PM

Just wondering if this is a normal condition. The Allison 1000/2000 Operator's Manual only covers the Shifter type gear selector, but the WH Owners Manual does cover the Pushbutton Shift Selector.
It indicates the Park Pawl will engage when the "P" is selected, then to apply the Foot apply park brake should be applied to ensure the mh is safely parked.

OK:
When I press the "P" selector Park button, without first engaging the Foot operated Parking Brake, I hear a significant "CLUNK" sound (Park Pawl engaging??) from the transmission area below. Then I engage the Foot Park Brake. Correct method as instructed.

However, if I first engage the Foot Park Brake, and then press the "P" Park button, there is virtually no sound, just a slight vague sound. Is it possible that the Park Pawl does not actually find it's lock position?

Just wondering if the Park Pawl clunk is normal/safe? Is it something that needs adjustment/servicing?

Your own experience would be appreciated, before I take my rig in next thursday for a front engine leak, under warrantee.

Thanks, Edouard.

Mr JP · 10-22-2010, 05:38 PM

Edouard; I have done the park scenario both ways as you have described and I do not hear any noise at all. Not sure what the problem would be but I would have it checked. Good Luck JP

DriVer · 10-22-2010, 08:39 PM

Quote:

Originally Posted by Edouard

When I press the "P" selector Park button, without first engaging the Foot operated Parking Brake, I hear a significant "CLUNK" sound (Park Pawl engaging??) from the transmission area below. Then I engage the Foot Park Brake. Correct method as instructed.

However, if I first engage the Foot Park Brake, and then press the "P" Park button, there is virtually no sound, just a slight vague sound. Is it possible that the Park Pawl does not actually find it's lock position?

Here's what I think is going on. When you set the brake, the drive line becomes locked up. Applying the AAPB or Park just engages the pawl and quite possibly the absent of movement in the drivetrain may be allowing the pawl to engage more quietly. I'm thinking like this. If you ring a bell it will sound. Now hold the bell (apply the brake) and ring it, it'll make a lot less sound.

In my expereince when you select park on a push button shifter - the park function works just fine.

Joe Gilbert · 10-24-2010, 08:26 AM

I'm sure it's an old age issue and I'm wrong but I thought the W24 had no pawl; only the AAPB.

JoeG

DriVer · 10-24-2010, 08:40 AM

Quote:

Originally Posted by Joe Gilbert

I'm sure it's an old age issue and I'm wrong but I thought the W24 had no pawl; only the AAPB.

Joe, Currently "ALL" W Series motorhome chassis (except equipped w/ the 4L85e) with Allison transmissions since model year 2006 have had a parking pawl including the W24.

Allison began providing WCC and others with parking pawls on the Series 1000 and 2000 series transmissions for quite some time. I believe the change was implemented with the Gen IV TCM and 6 Speed upgrade. If I'm off on the exact timeline, I apologize in advance but the timeline is very close.

AAPB is still used by Workhorse on the UFO chassis which does not have a parking pawl and yet does have a series 2000 Allison transmission. The braking system on the UFO is called HPB and is made by Wabco.

Edouard · 10-24-2010, 05:57 PM

Well, whether it has a Auto Park Brake, a parking pawl, which is questionable, since the manuals I have contradict both ways, I am going to contact my local Allison truck center tomorrow and see what they say about the 'CLunk" and posibly have it looked after.
Does not seem normal to have it make that 'loud enough' noise, everything else about the 2150 tranny is so smooth and quite. Will give you all an update.

Thanks everyone, Edouard.

DriVer · 10-24-2010, 06:36 PM

Quote:

Originally Posted by Edouard

Well, whether it has a Auto Park Brake, a parking pawl, which is questionable, since the manuals I have contradict both ways, I am going to contact my local Allison truck center tomorrow and see what they say about the 'CLunk" and possibly have it looked after.

Edouard, 1st please excuse the mention of AAPB in my previous post. You do not have an auto apply brake. Your push button shifter is connected by wire to an actuator which is bolted on the side of the transmission. The foot brake is connected via cable to an in-line brake on the drivetrain.

An AAPB applies a hydraulically operated in-line drum brake on the drive train and has nothing to do with a parking pawl.

Edouard · 10-26-2010, 09:45 AM

Hi DriVer et'al....
Just came back from my local Allison dealer, their mechanic came out and I went through the P selection from D, from R and from N. Each time there was an audible engaging sound.
When done he brought me into the shop and pulled out the 8 or 9 inch diameter flat tooth gear assembly, then pulled out a loose parking pawl and explained to me how sometimes the pawl will bear down to lock-in, but be on the raised flat tooth gear, and the high pressure results in it causing it to push into the next open gear tooth causing the audible noise, no fear of any damage, that's how it's designed, in the case where the pawl tooth falls directly into or very near the open tooth it just slides in more silently.
If as I mentioned earlier I apply the Foot Park Brake first, that constricts the toothed ring gear from rotating when I apply the P selector, so the pawl must just sit against the top flat edge or the tooth, until I release the Foot park brake to move the MH.
Neither the large toothed ring gear nor the pawl are tapered to allow a smoother interaction from what I saw, both are basically square edged.
So, I guess I could apply the Foot Park Brake before the P selector when parking, and release the P selector before the Foot Park Brake before moving the RV, which would avoid any adverse wear or noise, if that makes sense.
Strange, as others here with the W24 6 Speed chassis have no audible at all when applying the P selector.
Edouard.

DriVer · 10-26-2010, 10:27 AM

Quote:

Originally Posted by Edouard

Strange, as others here with the W24 6 Speed chassis have no audible at all when applying the P selector.

Edouard, My original "guess" was pretty close in regard to the tension on the drive line attenuating the sound of the parking pawl.

Edouard · 11-01-2010, 02:20 PM

Correction on the Title, our tranny is a 2350MH tranny, not 2150.

I have been doing some studing and found these Allision sites which may be of interest, if you are not already aware:

"Participating OEM & Allison Distributor/Dealer Warranty Document Only"
http://www.allisontransmission.com/s...t=SE0612EN.pdf

The 2009 Allison Revision of the WH 1000/2000 Operator's Manual.
Page 14 States: the MH 2000, 2100, 2350, 2500 & 2550 Do Not Have A Park Pawl, however, page 18 states: All MH 1000, 2200, 2350 & 2550 with P Park Position, does have as indicated P Park = RANGE: Neutral* (With Park Pawl Engaged)
However, the new version does have added info which may be helpful to all.
http://www.allisontransmission.com/s...t=OM3364EN.pdf

And this also relates to the 1000 & 2000 MH trannys, Revision 4. August 07.
http://www.allisontransmission.com/s...t=SE0100EN.pdf

All of these documents can be easily copied as Bookmarks &/or Documents files.