What is this piece and why is it so loose?

[FLtractor 56]

Noticed on my new to me 1966 856, this metal piece with the black round spoke knob has no tension on it at all.. what is it for and how tight should it be? 

[SylvanLakeWH 28,457]

That adjusts your implement lift handle... allows you to have implements higher or lower when you are using the large implement handle right next to it.

[FLtractor 56]

6 minutes ago, SylvanLakeWH said:

That adjusts your implement lift handle... allows you to have implements higher or lower when you are using the large implement handle right next to it.

Oh ok. So the hitch height especially when towing a yard trailer 

[ri702bill 9,455]

Up here in New England it is super useful to set & hold a snow plow to just skim over grass after the pavement ends.....

 

Edited April 9 by ri702bill

[FLtractor 56]

29 minutes ago, ri702bill said:

Up here in New England it is super useful to set & hold a snow plow to just skim over grass after the pavement ends.....

 

So to bring my hitch all the way to the maximum height … is that the loosest setting mine is at now with zero tension or the most tension? Which would also mean the deck at its highest position too correct?

[ri702bill 9,455]

8 minutes ago, FLtractor said:

mean the deck at its highest position too correct?

Looks like you have a gear drive deck. The tops of the two "wings" under & between the frame rails limit the upward movement when up against the frame.

[squonk 43,843]

11 minutes ago, FLtractor said:

So to bring my hitch all the way to the maximum height … is that the loosest setting mine is at now with zero tension or the most tension? Which would also mean the deck at its highest position too correct?

When you lower the lift arm, it contacts the metal rod sticking out. If you tighten the knob it brings the metal rod up higher hence raising the lift arm and raising the deck height

[gwest_ca-(File Mod) 11,493]

Sometimes that knob will spin off on it's own from vibration and the L-rod falls out unnoticed and lost. A plastic cap over the end of the treads prevents this from happening.

[8ntruck 7,842]

That knob is not for adjusting the mower deck cutting height - the gage wheels on the deck do that.

 

It adjusts the 'down' position of other implements - the snow plow probably the most common one that uses this feature.

[rjg854 12,217]

Also works well for adjusting the height of a grader blade. Letting the blade down for down pressure, or holding it up enough to just skim over the top for dressing up work.

[Bar Nuthin 1,088]

17 hours ago, FLtractor said:

Oh ok. So the hitch height especially when towing a yard trailer 

 

Not unless you have a special hitch that has a cable connecting it to the lift arm (commonly referred to as a sleeve or slot hitch).  Most tractors have a standard drawbar for towing small trailers. lawn rollers, etc,

The knob controls how far the lift arm is allowed to be lowered. Unless you're using a plow or grader blade - it should be left loose. As @8ntruck said, it is not for setting mower deck height - that is controlled by the deck's wheels.

Edited April 10 by Bar Nuthin

[FLtractor 56]

1 hour ago, Bar Nuthin said:

 

Not unless you have a special hitch that has a cable connecting it to the lift arm (commonly referred to as a sleeve or slot hitch).  Most tractors have a standard drawbar for towing small trailers. lawn rollers, etc,

The knob controls how far the lift arm is allowed to be lowered. Unless you're using a plow or grader blade - it should be left loose. As @8ntruck said, it is not for setting mower deck height - that is controlled by the deck's wheels.

My 856 has a cable that connects from the lift handle to the hitch.. seller told me it would be great for lowering hitch if I wanted to leave a trailer when towing it. 
so then how do I bring the deck height all the way up farthest from ground when towing to avoid bottoming out?

[SylvanLakeWH 28,457]

For clarification, folks are saying you don't use the handle adjust knob to set deck height. But it absolutely does impact how high the deck will raise when it's "hanging". 
 

Play around with it. Turn the knob one way a bunch and see impact on lever up and down... then turn it a bunch the other way and repeat... it will be obvious...

[squonk 43,843]

55 minutes ago, SylvanLakeWH said:

For clarification, folks are saying you don't use the handle adjust knob to set deck height. But it absolutely does impact how high the deck will raise when it's "hanging". 
 

Play around with it. Turn the knob one way a bunch and see impact on lever up and down... then turn it a bunch the other way and repeat... it will be obvious...

Exactly. If you're going to mow really high grass and want to cut it in steps you can lower the deck but control it's height with the knob.