Gearbox Trouble

[Guest]

The gearbox on my Petter AB1W is jammed in forward. I have checked all controls and cabling, and the problem is in the box itself - the lever won't move. As the engine itself is fine, I don't want to have to scrap it despite its age. Anyone got any prime candidates for the source of the problem?

 

[oldjohnnyb]

I have experieced locking up of a Hurth gearbox. I solved the problem by turning the engine in the opposite direction to it's running mode. It was a club boat and I am aware that the gear box failed the following year.
It was eventually replaced with a Hurth hydraulically operated box. The only trouble with a hydraulic box is, you cannot stop the prop. turning by putting the control in reverse.
I understand locking up happens on manually actuated boxes when the Morse control is operated too quickly from ahead to astern or vic versa.
John

 

[charles_reed]

The forward gear cone has seized in position.

Try turning the input shaft backwards, that should do the trick

Then drain the old oil was out, rinse thoroughly with kerosene and refill with nice clean fresh engine-grade oil.

Check the adjustment - with the engine stopped, putting the box in forward gear should just make the output shaft difficult to turn

 

[Guest]

I've just been down to try this. Assuming the Alternator drive pulley is on the input shaft, I have turned it a few turns backwards, but no joy. Still in ahead, and selector lever still stuck.

 

[charles_reed]

Try with one person turning and the other trying to disengage the selector.

If that doesn't work, drain the old oil out and replace with kerosene.

In the final analysis you may have to take the box apart and free off the cone clutch that way.

 

[Guest]

I have a Sabb engine and gearbox Which requires the prop shaft to move forward and back to engage forward and reverse gears. It got stuck in reverse caused by a pice of rope getting stuck between the prop and the outer shaft Could yours be something similar
Paul

 

[oldjohnnyb]

check oil to use

Engine oil is not necessarily the right stuff to use. Hurth gear boxes I have had dealings with required transmission oil. The same stuff you put in car automatic gear boxes.
John

 

[Guest]

I don't think anything is supposed to move like that in my set up. but I did pick up something earlier in the summer which got caught on the prop and slightly gouged the rudder. I never saw what it was, but I guess it would have put some stress on the whole drive train.

 

[oldjohnnyb]

horrible thought

When the Hurth box I was involved with locked up, the engine stopped dead. Everything was locked up, the engine shaft, the output shaft, and the control shaft. I had to use a stilson wrench (pipe wrench) on the crank shaft (which terminated as a power take off) to turn the engine in the reverse direction.
It is evident that your engine is easy to turn.
Is the output shaft on your box locked up? If it is, it is possible that something has sheared between the engine and the box.
John