JD 445 Mower Deck (48") Throwing Drive Belt

[Beemie]

Mower deck just started throwing the belt immediately on startup. Put it back and it immediately throws it again.

All spindles appear not be bound up and when the transmission is engaged with the belt off the pulley seems to spin true.

I can't recall when the belt was replaced but I don't think it is original as it it looks ok. Maybe replaced once since 1997 but it's not cracked or frayed.

Deck has been stored outside since new in 1997 and is in original condition except for noted belt.

The idler tension spring doesn't seem to require significant muscle to remove and replace it so I wondered if that might be the issue.

Any ideas?

 

[beenthere]

First idea that comes to mind is a spindle bearing froze up.. or an idler spring broken.. after that, don't know.

:welcome: to TBN

You will get some good help here..

 

[Beemie]

First idea that comes to mind is a spindle bearing froze up.. or an idler spring broken.. after that, don't know.
:welcome: to TBN
You will get some good help here..

As I wrote, all pulleys are free.
The spring is in tact but I don't know if it's gotten lazy. Somehow I expected more resistance when I reset it.

 

[beenthere]

Deck has been stored outside since new in 1997 and is in original condition except for noted belt.

Maybe good idea to get a spring and also a new belt.

 

[Spanner]

Mower deck just started throwing the belt immediately on startup. Put it back and it immediately throws it again.

All spindles appear not be bound up and when the transmission is engaged with the belt off the pulley seems to spin true.

I can't recall when the belt was replaced but I don't think it is original as it it looks ok. Maybe replaced once since 1997 but it's not cracked or frayed.

Deck has been stored outside since new in 1997 and is in original condition except for noted belt.

The idler tension spring doesn't seem to require significant muscle to remove and replace it so I wondered if that might be the issue.

Any ideas?

Usually the spring tension is the issue. A weak spring will allow the belt to 'whiplash' upon engagement and it derails easily as a result.

Also, however, consider the outdoor storage issue. 20 yrs is a while. If the mower deck shell has degraded due to corrosion (and we see that a lot down here in NZ) it will 'flex' when engaging the belt drive. That, coupled with a weaker spring is double-trouble. Check your deck for flex. Take it off the tractor and turn it up on its back edge. Use a hammer to tap the underside surface and see if rust flakes off or chips off like a ship does.

Two possible causes for you to look at.

Third possibility, before I go, check the nylon bushes in the Tensioner Arm Pivot Post. Excessive wear of these bushes causes the tensioner to become mis-aligned leading to belt de-railment also. That tensioner should have a plastic cap over the top of the post to protect the felt washer and bushes from excessive dust. That cap is often missing.

Regards.
:wrench:

 

[Beemie]

Turns out that the belt that didn't look bad was significantly worn compared to a new one.
New belt and spring did the trick.
Pretty expensive belt but it's quite a piece of workmanship to get wear surfaces on all the faces.
Hopefully these last the next 20 years too; I'll be gone by then.

 

[Spanner]

:thumbsup: