816 wrecker question

[martinsaunders06]

hello my name is martin and i live in the uk,back in august i bought a 816 wrecker and im sure back then when going into first and reverse gear i got an air venting noise from valves on gearbox.now it only seems to vent when engaging reverse?can any one confirm that it should do it in both reverse and first or is just reverse correct.many thanks martin

 

[m139h2otruck]

All the manual transmission 5 tons should vent or dump air when shifted between reverse and neutral. The air being dumped is the opposite side of the sprag shifter cylinder being vented. Best you check for correct operation of the shift cylinder before you run it much or you could wreck the transfer case if it is stuck in the wrong direction from which you wish to go. The manuals will help you with this. Have you had any banging or odd noises when you try to drive off after shifting forward to reverse or reverse to forward?

 

[Scrounger]

The 800 series trucks have an air line that feeds the transmission with air and two lines that run from the transmission to the transfer case. When one places the transmission into first or reverse poppets are engaged that sends air to the transfer case locking the truck into six wheel drive for maximum traction. When one shifts into neutral or any other gear the Sprague unit in the transfer case should unlock till it senses wheel slippage in the rear. If you are not hearing the air actuating the poppet it could be something as simple as oil/grease on the cylinder to a bad o-ring. I would try to work the transmission shifter back and forth to see if that frees it up. Of course there has to be air in the system. If that doesn’t fix it you may have to take the top cover of the transmission to clean or maybe replace an o-ring.

 

[martinsaunders06]

thanks for your reply,not noticed any noises yet but its the lack of venting/dumping when going into first that caught my attention for im sure it did so 3 months ago.i take it sounds like its putting the sprag into reverse but if its not venting when going back to first then its taking it out of reverse when i go forward?

 

[Scrounger]

When things are working correctly, one will hear the same sound when shifting into first or reverse. If it isn’t disengaging the Sprague unit when one drives damage can be done. More likely you will feel a dragging or scuffing sound if the Sprague is not disengaged.

 

[martinsaunders06]

only recently discovered steel soldiers and think its ace,been looking back through previous posts on 5ton and it a mass of information especially as cummins stuff over is rare and you see or know of any on the rally circiut.thanks for replies on air shifter as i will now look into poppet valves/cyl etc.good trucking,thanks guys

 

[73m819]

the tms show the trans air setup really well