| Author |
Message |
    
Pete Clark
New member
Username: pontoonpete
Post Number: 1
Registered: 06-2014
| | Posted on Tuesday, June 17, 2014 - 09:09 am: | 
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Hi everyone interesting forum, I have a Parsons gearbox on a Ford D4 When I increase the engine revs the prop shaft revs stay the same and sometimes drop.
Regards Pete. |
Eric hoare
Member
Username: eric
Post Number: 28
Registered: 03-2006
| | Posted on Saturday, June 21, 2014 - 04:58 am: |
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Whether or not it is the same gear box Pete, I had a box that was doing the same and on investigation found the "wet clutch" had worn down. As replacements were hard to get, I took the rivets out and placed a steel shim behind them and re-riveted, this brought the pads further out. This worked fine. It may help.. |
Andrew Munns
Senior Member
Username: johnoxley
Post Number: 121
Registered: 04-2010
| | Posted on Saturday, June 21, 2014 - 05:48 pm: |
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Assuming old gearbox with contracting band brake? On a Union box I once located and bought a piece of brake lining from a brake and clutch specialist and riveted same in place of the original lining. Used soft rivets and made sure they were well counterbored. |
Pete Clark
New member
Username: pontoonpete
Post Number: 2
Registered: 06-2014
| | Posted on Sunday, June 22, 2014 - 04:34 pm: |
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Thanks for those replies, both helpful but I'm not too sure that I know enough to delve that deeply I was hoping that it might be adjustment. there are two brass nuts that allow access to a lock nut/slot type (I guess) adjuster but i have never had much to do with gearboxes so I don't know.
Regards Pete. |
Andrew Munns
Senior Member
Username: johnoxley
Post Number: 122
Registered: 04-2010
| | Posted on Sunday, June 22, 2014 - 05:03 pm: |
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If it is a contracting band onto a drum, there will? be adjustment nuts. You really need to find a manual or find someone with knowledge on these boxes to avoid setting the adjustment too close, which leads to dragging and wear + heating through friction. Firstly try adjustment, and if this fails, replace the lining, which involves pulling the box and partial dismantling.
If the box is off and apart, it would be sensible to drop in new bearings and seals. |
Pete Clark
New member
Username: pontoonpete
Post Number: 3
Registered: 06-2014
| | Posted on Tuesday, June 24, 2014 - 10:55 am: |
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Thank you Andrew,
I will try that, it is a contracting band there are plates on either side for access to the lock nuts and two brass plugs at access the adjusting bolts.
I will tighten these and see what happens. Thanks again Regards Pete. |
Pete Clark
Member
Username: pontoonpete
Post Number: 4
Registered: 06-2014
| | Posted on Monday, July 14, 2014 - 06:23 am: |
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Just to tidy this one up, based partly on observation and partly on assumption. There is a big threaded brass collar right in the center on the main shaft, this is the anchor point for the L shaped activators if it is not far enough forward the clutch slips ( a bit like riding the clutch on a car ) ie.Not enough pressure on the plates, but, if it is too far forward ( tight ) it causes friction between the thrust and the activators. Once this is set, giving full drive ahead the brake band can be set. I set mine in neutral and just backed off when the prop shaft started to catch. This has given me full astern. I have done a four hr. Test so far and all seems fine. I must stress that this is only my opinion, and thanks again to the members who helped me with their answers.
Regards Pete. |
