 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
rparigoris
Joined: 24 Nov 2009
Posts: 796
|
 Posted: Mon Jan 04, 2010 11:11 am Post subject: What happens if you overspeed a 91X? |
 |
|
Hi IraI am curious what failure occurs if you overspeed a 91X?You mentioned:" what will happen is that above 6000 engine rpm, the speed of the hydraulic valve lifters is inadequate to completely open and close. They essentially float out of synch and get bent out of straight by the cams."I am not sure what you said, do the hydraulic valve lifters themselves get bent by overspeed? I always assumed that the mass of valve train has more inertia than can be held by the valve springs where the valve lifters are in contact with the cam (valve float)? Then a valve is left opened where it shouldn't be and a piston contacts the valve and bends the valve, and probably also the pushrod? Another question, since the 912S has a different cam grind than the 912 or 914, does overspeed problems occur at the same RPM as 912 or 914?Thx.Ron Parigoris [quote][b]
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
 |
bob(at)fly-ul.com
Guest
|
| Posted: Mon Jan 04, 2010 11:47 am Post subject: What happens if you overspeed a 91X? |
|
|
On 11:10 AM 1/4/2010, rparigor(at)suffolk.lib.ny.us wrote:
| Quote: | Then a valve is left opened where it shouldn't be and a piston contacts the valve and bends the valve, and probably also the pushrod?
|
For what its worth, In the 912 Line maintenance manual (05-50-00, section 3.3), the inspections exceeding max RPMs are addressed. Yes, Pushrods are on the "list" of things to inspect.
--
Bob Comperini
e-mail: bob(at)fly-ul.com
WWW: http://www.fly-ul.com
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
|
rampil
Joined: 04 May 2007
Posts: 870
|
| Posted: Mon Jan 04, 2010 5:19 pm Post subject: Re: What happens if you overspeed a 91X? |
|
|
Hi Ron,
It did not occur to me that the cams are different on the different
models.
As for different frequency response of the valve train, sounds like a
factory question. No one else would have an engine closely instrumented
to detect the float and over-sped to destruction. The cams should only
be different in amplitude, not angular change. The float is a
phenomena of frequency response so it should be a function of spring
compliance and push rod inertance. (Hows that for an x engineer)
Happy New Year!
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
_________________
Ira N224XS |
|
| Back to top |
|
|
davidjoyce(at)doctors.org
Guest
|
| Posted: Tue Jan 05, 2010 2:12 am Post subject: What happens if you overspeed a 91X? |
|
|
Ron, The UK Rotax agent procedure for modest overspeeding (between 6000 &
6100 rpm) was to remove the push rods and check them for straightness using
a sort of cradle and a micrometer measuring device. If that is OK no further
checks are needed.
Regards, David Joyce, G-XSDJ
---
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
|
rampil
Joined: 04 May 2007
Posts: 870
|
| Posted: Tue Jan 05, 2010 7:12 am Post subject: Re: What happens if you overspeed a 91X? |
|
|
Hi All,
The push rod check is all that is required IF the overspeed <6200 AND
less than 1 minute in duration. Overwise, the requirements escalate
expensively! This is per page 10 of the Unscheduled Checks section
of the new Line Maint manual(912, 912S).
Cheers,
Ira
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
_________________
Ira N224XS |
|
| Back to top |
|
|
lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
|
| Posted: Tue Jan 05, 2010 7:58 am Post subject: Re: What happens if you overspeed a 91X? |
|
|
| bob(at)fly-ul.com wrote: |
For what its worth, In the 912 Line maintenance manual (05-50-00, section 3.3), the inspections exceeding max RPMs are addressed. Yes, Pushrods are on the "list" of things to inspect.
--
Bob Comperini
e-mail: bob(at)fly-ul.com
WWW: http://www.fly-ul.com |
Unfortunately the manual leaves out the following step in this case:
- go to bank (with gun)
LS
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
_________________
LS
Titan II SS |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
