Identify shaft brake

[bill424]

Attacked is a picture of a shaft brake attached to a Yanmar diesel. Although the hydraulics are working and the retraction spring reluctantly so, the little brake pads (I assume) don't slow the shaft at all so the shaft freewheels when the engine is in neutral. This is apparently a bad thing

The spring being bent suggests to me that it wasn't installed properly, perhaps that there's a piece missing but my Google-** can't find out what model and manufacturer the brake is, so it's hard to prove. Any ideas what it is?

[pcmm]

Why is the shaft free-wheeling in neutral a bad thing? That what Yanmar recommends for their transmissions

[kenbo]

Originally Posted by pcmm

Why is the shaft free-wheeling in neutral a bad thing? That what Yanmar recommends for their transmissions

This^

But if you want to renew your brake pads you can buy brake friction material, cut it to fit, and rivet it onto the backing plates. That's the way we did it before disc brakes and there was an Autozone on every corner. I guess I'm showing my age...

[bill424]

I had read that the freewheeling causes undue heating in the transmission, but if Yanmar says otherwise that's great. I omitted to mention that the boat uses a Walters V-drive - could that be the reason to stop the shaft?

[Uncle Bob]

Plus a locked prop will cause more drag and slow the boat down.

[deblen]

If your V-drive model is equipped with it's own oil pressure pump,so that it's bearings are lubed by this pressure pump-lubrication only occurs when the V-drive is being driven by the operating engine.
If you stop the engine & tow or sail the boat & the prop spins the shaft & rear output shaft of V-drive,you will destroy the V-drive bearings.
The same will happen to Borg Warner Velvet Drives,& possibly other pressure lubed gear boxes. If your gearbox has hydraulic hoses,verify with gearbox mfgr to find whether this can happen.
Small engine gearboxes,such as Hurth,Volvo,etc are not pressure lubed,but are splash lubed by their turning gears,so turning the output shaft should not cause harm. Verify by checking with gearbox mfgr.I wouldn't always trust the engine mfgr/salespeople for gearbox info.
In the case of pressure lubed gearboxes,the shaft must be locked.
Cheers/Len
http://www.svsarah.com/Sarah/Manuals...%20V-Drive.pdf

[bill424]

Originally Posted by deblen

If your V-drive model is equipped with it's own oil pressure pump,so that it's bearings are lubed by this pressure pump-lubrication only occurs when the V-drive is being driven by the operating engine.
If you stop the engine & tow or sail the boat & the prop spins the shaft & rear output shaft of V-drive,you will destroy the V-drive bearings.
Drive.pdf[/url]

Thanks. From the pictures I have, the V drive appears to have an oil pump driven mechanically by the turning shaft from the engine.

It's not clear to me what happens if the prop-shaft spins the V-drive instead, but your explanation suggests that that's why the shaft brake was installed, or at least why someone thought it necessary

Since it's not my boat (yet), I'm struggling a little with the engine replacement history that led to this.

Thanks for your help.

[GordMay]

You need to check the manual, for your particular transmission.
Yanmar says [TECHNICAL BULLETIN Ref No.: YMTQTB11-017, Date: October 18, 2011] to leave it in neutral, & use a shaft brake [if you choose]:
➥ http://www.endeavourowners.com/dscsn...TQTB11-017.pdf

Originally Posted by Yanmar

“TECHNICAL BULLETIN Ref No.: YMTQTB11-017, Date: October 18, 2011]
" To : Yanmar Marine Regional Head Quarters and All Yanmar marine distributors
Subjects : Yanmar Sailboat engine control lever position during sailing under sail with engine stopped
1. Introduction
Yanmar wishes to inform you about the instruction of the control lever position during sailing under sail with engine operation stopped. This instruction is subjected to mechanical type gearboxes and sail drives only.
2. Operation instruction
2-1 Mechanical Cone clutch :
Applicable models: Sail Drive: Models SD 40, SD50 and SD50-4T
Marine gear: Models KM2P, KM35P, KM35A and KM4A
When mechanical cone clutch type gearbox or sail drive is equipped with the following propeller:
a. Fixed propeller:
When sailing under sail with engine operation stopped put control lever into Neutral. The output shaft keeps rotating.
Notice:
When control lever is put in Reverse position, cone slippage will be introduced and void your warranty and there is possibility that the clutch doesn't disengage. This can be a problem for engine re-starting.

There are options to stop free rotation of propeller-shaft if customer doesn’t want occur noise from rotating propeller:
1) For sail drive: install folding propeller or Feathering propeller instead of fixed propeller.
2) For marine gear: install the Shaft - Lock device, Yanmar does not supply, on the propeller shaft. ...”

Walter V-Drive: [Don't know if these apply]
Owners Manual ➥ https://www.tigeowners.com/downloads/walter_vdrive.pdf
Installation & Service Manual ➥http://www.svsarah.com/Sarah/Manuals...%20V-Drive.pdf

[pcmm]

Originally Posted by bill424

I had read that the freewheeling causes undue heating in the transmission, but if Yanmar says otherwise that's great. I omitted to mention that the boat uses a Walters V-drive - could that be the reason to stop the shaft?

Yanmar's instructions about freewheeling is for YANMAR transmissions, you have the unusual case of having a non-Yanmar transmission connected to a Yanmar, honestly in my 30 years boating and helping a lot of others with mechanical issues, this would be a first. You need to find the manual for your Walters transmission, they might have completely different instructions. Too bad if you have to brake it because a stopped prop has a lot more drag than a freewheeling prop.

[kenbo]

Call Walter Gear 201-656-5654, they are very knowledgeable. Have your model number at hand.

[skipperpete]

Originally Posted by bill424

I had read that the freewheeling causes undue heating in the transmission, but if Yanmar says otherwise that's great. I omitted to mention that the boat uses a Walters V-drive - could that be the reason to stop the shaft?

How good is your oil pressure? I assume it picks up from the engine lube oil and at low hot idle its not unusual for the brake to drag and wear out the linings. I would expect smoke and a burning smell if this was happening. I’ve not yet seen a Walter vee drive that required or had a shaft brake.

[bill424]

It remains a mystery for now. The V-Drive has its own cooling and oil systems.

Cooling water has its own seacocks, though I'm unsure how the flow is managed.

Oil again is self contained and mechanically driven by a pump that the main shaft from the engine spins.

For now I'll go with Deblen's answer and assume that the brake should be fixed unless the yard's mechanic can explain why it was done.

Thanks.

[bill424]

Duplicate

[skipperpete]

I did a bit of a search through the Walter workshop/installation manual and couldnt find any reference to a shaft brake (or instructions for towing or freewheeling), not even a pic in google images…. But I did discover that I actually have one of these vee drives ( close coupled version) in the “unloved but too interesting to sell for scrap” section of my workshop, I’ll be back there in another week and might open er up for a look. It came off the rear of a perkins 4-108 with a lot of hours on it, sailing yacht…. No shaft brake and in this case no possibility to install one either with the coupling under the machinery… well under.

[bill424]

The shaft brake is attached to the Yanmar and is plumbed into its hydraulics for activation. The V-drive is severval feet away and as far as I can see, completely distinct from the brake.

Oil analysis of the V-drive's (separate) oil supply came back clean, so I don't think it has been grinding bearings due to the brake being ineffective.

I'm pretty baffled by the whole thing, especially that I can't find anything about shaft brakes on Yanmers apart from references to their tractors (which I didn't know existed).