hwh rap1940 failures - Printable Version

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+--- Thread: hwh rap1940 failures (/showthread.php?tid=7925)

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hwh rap1940 failures - encantotom - 04-01-2024

i deal with these alot since i sell the rebuild kits for them.    i know i have posted about this before but thought i would refresh everyone.

these valves were used in newell leveling sytems from the late 80's to about 2003.  in the earlier coaches newell made their own manual leveling system with toggle switches on the dash (my 90 had that).  they still used these valves or the earlier kip valves that were the same except for the coil.  when they went to the hwh leveling system they all used the rap1940 valves

they are also used on a wider range of foretravels and any other coach of that vintage that used the hwh leveling system.  

these valves are designed for much higher activation rates than what the leveling system or ride height system gives.  so why do they faieaning leak).  first of all the coils almost never fail.  i have only seen a handful fail (one was on tims coach when he was here doing his slide seal and i had a spare coiil to replace it with)

so...the leaks come from 3 different ways from what i can see.  i have replaced dozens of these things on mine and friends coaches.  

1.  i attached a picture of 20 some old plungers that are inside the valves.  you can see the indented ring in the blue seal.  the orfice inside the valve body is raised up and kinda has a sharp edge.  when the valve is not energized, the spring on the plunger inside the stem pushes the seal on the plunger onto the orfice....thus sealing it so no air can pass.  the only time air should be passed from the valve is when the plunger is pulled up by being energized and allowing air to pass to or to be let out.  when you are in "raise" mode on one of the valves, the raise solenoid is energized, pulling the plunger in and allows air to flow from the air system to the airbag you have selected.   conversely, if you are wanting to "lower" the air bag, the lower solenoid is energized and the air is let out of the airbag by the plunger being pulled in and air being let out.  

that seal is the culprit.....if it leaks when closed, then you can have the airbag slowing raising....or slowing being let down....

these are just a rubber seal....1.  as it gets old it gets less rubbery....2.   our systems are not clean systems.   water and rust and junk is often in them, and if a piece of anything small goes through and gets between the plunger seal and the orfice, it can make a little dent and cause it to leak.  slowly. 3.  it is possible though incredibly unlikely that the spring that forces the plunger to seal against the orfice has gotten weak.  my kits have new springs to eliminate that issue.  

as we have all learned, if you have a corner of the coach that is dropping or raising then there are lots of things that can cause it.  air lines, fittings, the airbag, the seal leaking like i have described above, etc.  it is not a sure thing to replace the plunger and spring, but does eliminate that with a fairly easy job.  

i posted  a few other pictures.  the fender washer is actually my tester to see if the valve is energized.  if you dont have one a screwdriver will work (ha)   when the valve is energized the coil is just an electromagnet.  so if you put the washer on the nut or end of the stem on the valve it will stick.   dont need no expensive meter....ha

the other is of a valve that was replaced.   i have seen a number of these from rigs.   it was tightened too tight in the manifold and in so doing distorted the inner brass ring that holds the o ring.....why does that matter?  my picture isnt great, but it shows with the o ring out the damage that was done.  that brass outer lip was distorgted and it broke a hole in the bottom that allows the air to leak by the oring to the manifold.   do not overtighten these valves in the manifold.  i put some o ring grease on them and just snug them in.  the o rings seal them, not metal to metal contact between the valve body and the manifold.  

well, thats all folks.   

hope that explains some things about these valves and how they leak and fail.  

with keeping your air system clean of water and rust, once you rebuild these valves they should last a very long time.  

later

tom

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RE: hwh rap1940 failures - BusNit - 04-01-2024

Dumb question, but to change the seals do I just unscrew the solenoids? The rears appear newer. The front is the one giving me issues as the front end will sag after a couple days.

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RE: hwh rap1940 failures - encantotom - 04-01-2024

Yes. Take the valve body off the manifold. Be sure to shore the front end up as it will drop. Give me a call and I can talk you through it

Tom

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