| Author |
Message |
    
Peter Fleming
New member
Username: discovery
Post Number: 2
Registered: 04-2015
| | Posted on Saturday, November 07, 2015 - 12:53 pm: | 
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Hi,
Does anyone have any diagrams or information on how the P5M gearbox works?
Thanks |
Hugo de Rrick
Member
Username: hugo_de_rrick
Post Number: 5
Registered: 10-2014
| | Posted on Saturday, November 07, 2015 - 03:51 pm: |
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Hello Peter -
Have a look @ the attached section through a P5 / 55 gearbox.
The drive is taken from the back of the engine via a pair of cones; one stationary - one rotating.
Moving the tram handle, or lever-style control handle moves the core of the gearbox (1) forward via a spring loaded barrel - this engages the direct drive forward gear (where the whole of the gear assembly spins)) or (2) backwards (engaging astern via a cone machined in the stationary gearbox housing). When in astern, the gear gear assembly is held stationary (by the rear cone) and the drive is taken via a three-lobed spline & the epicyclic gears in the centre of the gearbox.
The epicyclic gear train provides a reduction in shaft speed when astern which goes some way to offsetting the drop in propeller efficiency when spinning a propeller in reverse.
The gearboxes are pretty much bullet-proof - they really only suffer in the hands of a helmsman who partially engages / slips the drive to control way (wearing the cones), or contaminated oil.
I hope the above makes sense.
Holler if not.
Regards,
H.
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Peter Fleming
New member
Username: discovery
Post Number: 3
Registered: 04-2015
| | Posted on Sunday, November 08, 2015 - 01:15 am: |
|
Hi,
Thanks for replying.
We have the main gearbox in pieces as reverse gear would not engage and it was stuck in forward.After looking at it, what causes it to disengage out of gear?
Thanks |
Hugo de Rrick
Member
Username: hugo_de_rrick
Post Number: 6
Registered: 10-2014
| | Posted on Sunday, November 08, 2015 - 03:31 pm: |
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Hi Peter -
The gear assembly is driven backwards & forwards by the sleeve (highlighted yellow in the attached), which is moved fore & aft by the eccentrically mounted pin (circled in blue) on the end of the vertical tram-handle. Stuart recommended the following to release a 'stuck in forward' gearbox; put the gearbox into astern & use a wooden block and hammer to drive the shaft coupling aft. If the coupling isn't accessible, again put the gearbox into astern & tap the flywheel boss with a lead hammer...
H.
shaft. |
Peter Fleming
Member
Username: discovery
Post Number: 4
Registered: 04-2015
| | Posted on Sunday, November 08, 2015 - 04:42 pm: |
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Hi H,
Thanks again for trying to help us understand the gearbox.We understand how the sleeve works however there is no attachment to the gear assembly. We do not understand how it operates in both directions because of the lack of attachment.
Thanks
Peter |
Hugo de Rrick
Member
Username: hugo_de_rrick
Post Number: 7
Registered: 10-2014
| | Posted on Monday, November 09, 2015 - 03:10 pm: |
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Hi Peter -
The sleeve is sandwiched between the gear assembly & the shaft coupling. If the coupling isn't in place, one can go from neutral to forward, but not from forward to neutral, or from neutral to astern - the sleeve will just slide on the shaft...
I hope that clarifies things...
H. |
Peter Fleming
Member
Username: discovery
Post Number: 5
Registered: 04-2015
| | Posted on Monday, November 09, 2015 - 05:02 pm: |
|
Hi,
Thanks for all your help.
We just have to finish the restoration now.
Peter |
P5 / P55 gearbox cross section
