Bargain MTD 548 Repair Help... Veri Drive

[Bat135]

Hi

I recently picked up a lawn flight MTD 548 12hp 30 inch deck.

It was a bargain but a bit of a dog. Done all but one repair... and cant get my head around it.

The issue is it drives... cuts... starts from key now as bypassed safety switches... basically everything works apart from when I push in the brake/clutch pedal it does not stop the mower... and none of the ground speed settings from 1 to 7 work... it remains at same flat ground speed.

The blade speed (throttle setting is ok) just the brake does not work or the ground speed of the wheels (setting 1 to 7) on the rear right wheel fender.. a stick with settings 1 to 7.

So I can start it... cut the grass.. but to stop it is impossible apart from hack the choke up.. as ignition key not fully setup yet.

I can ram it in first... reverse and neutral whilst running without the need for the clutch/brake pedal.

Is the rear axle housing all the clutch stuff knackered... or is a spring missing... or is the veri drive stuck or seized.

Surely the brake should work though...

Having seen a video of the veri drive system actually moving when running g one of the pulleys nearly meets the other when working correctly with the clutch pedal.. mine dont move at all.. when running. As took the gear cover off so I could see the belts and pulleys when running.

Any ideas??

Regards

Paul.

 

[bertsmobile1]

THis mower uses the vari drive system with 2 drive belts both connected to a double pulley
The middle bit can slide up & down the change the diameter of the top & bottom sections of the pulley
So in effect it is the same as a set of stepped pulleys you see on pedistal drills for changing the speed
SO the first thing to check is that the middle bit ( called a sheave ) can slide up & down freely.

Exactly where the sliding sheave sits in the double pulley ( called a variator ) is determine by a tug of war between the tension spring on the rear belt and the tension spring on the front belt which is attached to the stop/clutch pedal.
The "gear / speed " lever limits how far the stop/brake pedal can return which changes the tension in the front spring .
These drives use special belts that are wider & thinner than standard belts .

Now the brake
The same pedal will have a rod that goes to the brake which is behind the right hand wheel
The rod pulls an arm with a twist in it that pushes on some pins that in turn pushes on a disc brake pad.
There are prone to rusting solid.
Remove the caliper but do not touch the middle nut , that is one of the adjusters .
Clean all of the parts , make sure the pins move freely and the pads are in good condition then reassemble
BEware as there will be 1 or 2 shims that go behind the brake pads , don't loose them .
When reassembled the lever should lock the disc before it gets 3/4 of the available travel.
If not adjust the center nut till it does.

Now because the brake is also on the clutch pedal there is an adjustment ON THE ROD to balance the braking and clutching so the brake does not come on till the belt is loose enough to slip or you will break belts like crazy.
I adjust them on the trailer ramp with the engine off and get it so the mower just starts to roll forward from clutch slip before the brake stops it
NOTE the brake is not progressive, it is all on or all off .

 

[dougand3]

Great explanation, Bert. I'm gonna copy it for when I get a vari-drive to rehab.

 

[Bat135]

Thanks loads... I wonder if one of the tension springs is missing? That you say is a tug of war between? Where are these exactly located?

The veridrive put should meet the put towards the back when the tension changes .. should I be able to move them by hand?

There is no resistance on the speed lever 1 to 7 at all.. it just flops around.

Could anyone show me a video on the first reply? As it's hard to see from words what things you say to check.

Thanks so much for your help : )

 

[bertsmobile1]

Take the battery out , drain the tank , remove the deck then stand the mower up on its bum
The rear top belt is in a triangle with the varidrive pulley the actual very large drive pulley & the tension pulley being held in place with a spring ( tug O war team 1 )
Push the stop/ clutch pedal down and look for the spring that pulls it back up ( tug-0-war team 2 )
When you can see the whole thing from 4' away it will be obvious
Poking your proboscus between the deck & the bottom of the mower will just crick your neck

There is a second system that does the same thing by moving the varidrive pulley
However we need the full make , model & serials off the tag under the seat if you want specific details

IF you stand back 10', support your camera on some thing solid so the photos you take a re clear & in focus then post them some might recognise what is missing or in the wrong place.
However if you are too lazy and just shove the phone under the mower don't expect any one to make any more effort than you do

 

[Bat135]

Ok

Yep. Understand.

Believe me.. I have made efforts.

Thanks for your advice.

Will upload a pic or video with a day or two and will be clear... as personally I thing a part is missing..

Thanks for the help. Hopefully it will help others to as nothing else on the net for this issue.

Check back for vid and pics soon.

Thanks in advance.

Paul.