Timberjack Forwarder 1210B Speed Issues

[mattpriest]

I am having 2 speed issues with my forwarder. First one, it is stuck in snail speed but displays turtle on the screen. Once it clicks into snail the speedometer also stops working. The odd time you will start it up in the morning and turtle along with the speedometer will work for half a day. Second, while its in neutral it will decide to go into high range (rabbit) and then back to turtle. It will continue to go back and forth really fast allowing the forwarder to drive itself making a horrible grinding noise until you shut it off or it stalls out. It will do this when the ladder is down and in park as well.

I am really hoping that someone can give me some insight on these problems because there has been no mechanics that have been able to help.

[nativewolf]

Where abouts are you?

[mattpriest]

Located in Barrie, Ontario

[barbender]

That's a tough one, but there's a few guys on here that may be familiar with that machine. @bushmechanic ?

[Skeans1]

Will the machine center? Or sit still well idling? When was the last time the charge filter was changed? Do you have the operators manual?

[mattpriest]

Sometimes it will sit still and sometimes it will not. When I first got it was changed but that was awhile ago and yes I have the manual.

[mike_belben]

How are the two speeds accomplished?  Is there a gearbox with a physical shift fork..  2speed hydraulic shift via a planetary gearbox?  switching the drive motors from a series to parralel plumbing by way of a 2 or 3 position solenoid valve? Stroking a drive pump swash plate to high flow?

[Skeans1]

The 2 speeds are done with a two speed gear box after the hydrostat motor, the snail mode is done with the swash plate angle in the motor. I'll have to look in my books but I have adjusted the swash plate on the pump to recenter the plate to get rid of the creep it's on the right side of the machine under the cab you'll have to remove the guard by the bogie to get at it. One other issue we've had in the past is there's a solenoid to the right side of the hydraulic filter on the right bogie side of the hydrostat motor that got stuck in one direction not allowing full travel speed. The solenoid should be snail travel in turtle mode issue, the other grinding if the machine isn't in a complete stop when shifting to high range or rabbit you will get this grinding.

[mike_belben]

What shifts that two speed trans?  Little gearmotor or something?

Id start with making absolutely sure the solenoid chassis have close to zero ohms relative to the battery ground post.  Id chomp jumper cables on to add expedient grounds first thing then see if any change.  

Step2 id verify the positive voltage is coming down the harness and getting to the solenoid, if not determine whether its getting into the harness or not.  Ecm pinout probably needed for this. 

[mike_belben]

The part about the machine self shuffling from fast to slow is making me pretty confident its a wiring issue.  A solenoid has a magnetic coil inside that pulls an iron core to it physically then a return spring kicks the core back. This probably shifts a small spool.   

A loose wire would toggle the solenoid like that but so would low enough voltage that the solenoid cant stay pulled in over the springs resistance.  When a low battery makes a starter solenoid rapidfire click, thats what youre hearing.  Insufficient voltage to conquer and hold the return spring.  If the machine starts good then its got enough voltage in the batteries so low voltage to the solenoid would likely be corrosion somewhere in the wiring or poor ground.. Either will create high voltage drop.  2 guys and a meter should be able to zero in pretty quick once the wires are ID'd. 

[bushmechanic]

Barbender I'm trying to forget what I know about a 1210 :D. Skeans1 has a good grasp on how it works and I agree with Mike...machine seems to have wiring issues. First of all it shouldn't move with the step down. Your going to need a mechanic who can read Timberjack wiring diagrams to get to the root of this problem. What year of machine is this?