My Tractor Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
Good morning y'all. I have a Gravely ZTHD-60 with 3100 hydros with a speed rating of 8mph. I understand this is probably overestimated but I'm curious of I could have something going on with my Gravely.

In a nutshell. The mower is great. Aside from a failed spring tensioner at 14 hours, it runs and cuts wonderfully. I have some rough areas in my backyard where the speed is not important. But my front lawn is very smooth and I'd like to get the most out of the mower. I checked the mowing speed with a GPS and was getting between 5.5 and 6mph. So there is some speed left on the table.

Is it common for this type of mower to be about 20 percent off the rated speed or is there something I should be looking at on the mower to help me get the most out of it? Belt tension? Hydro adjustment?

I'd appreciate your help.
 

·
Moderator
Joined
·
21,709 Posts
Check the max engine speed with a tach and compare to the max input rating for the hydro.

Also, check the tire pressures. Travel speed is determined by the height of the axle above ground (rolling radius). One psi pressure change will change that axle height by approximately 1/4".

Depending on how far off spec both are, you may find your 20%, or some portion of it.
 

·
Premium Member
Joined
·
3,456 Posts
There is also may be/should be/are some adjustment screws for the two levers that are used to even out the speed of both wheels (so pushing forward all the way with both levers results in you going mostly straight). They maybe adjusted so that both levers are prevented from moving as far forward as they could be, limiting your maximum speed. You could see if backing them off gets you back your top speed (and then just adjust one to get back to going straight).
 

·
Registered
Joined
·
12 Posts
Discussion Starter #4
Thanks. There are adustment/limiting screws located on the steering controls. However they are opened up enough that they do not limit the movement of the steering controls.

After a closer look there are linkages from the steering controls to the hydros that are adjustable. They are a bit complicated and I don't want to go messing with them without understanding how they work. I need to get my hands on a factory service manual. The mower has a 5 year warranty and I could take it in for service. But if I do that I'll wait until after the mowing season.
 
1 - 4 of 4 Posts
Top