Mowing PT 60" Mower

[Schultz]

PT 60\" Mower

I'm trying to sell the wife on the PT-422 with the 60" Mower. However, Hans made me a little nervous about the reliability of the mower. I want a good reliable mower since I, well more like the wife has around 3 acres to mow. I’ll use it for everything else.

Hans, and others, I have a few questions.
You mentioned the bearings & belts are shot every 300 hrs. For me that would be four or five summers, which might be acceptable if its just bearings & belts. But do you end up replacing the spindles, and other parts in the process.

How long do your exmark's or other mowers hold up before a rebuild warranted?
What's different about the commercial mowers?

How much do the bearing & belts cost?
What do you think the problem is, the bearings or the design?

Thanks
Tim

 

[hazmat]

Re: PT 60\" Mower

here's an example where "duty cycle" comes into play:

Hans uses his PT Commercially. he could be putting as many as 30-40 hours a week on the machine. He is also making his living with it, meaning he will drive it as hard as he can get away with in order to get the best return on his investment.

You / your wife will be mowing 2 hours at a time, once every 5-10 days (depending on weather).

Big difference.

I'd bet dollars to donuts that you will see less problems after 300 hours than hans has (not that hans is doing anything wrong, just different application)

A commercial mower should have beefier bearings & spindles designed for higher MTBF (Mean time before failure)

 

[Anonymous Poster]

Re: PT 60\" Mower

Power Trac makes a commercial deck with big tapered spindles and a more powerful hydraulic motor - I considered it but thought that for mowing once or twice per week - the standard would be fine for me - it is half the price - so I could actually buy another brand new one if it ever goes and be even (vs if I had bought the commercial one) now if I were doing commercial work - I would spend the money up front

does Hans have the commercial unit?
-edm

 

[Anonymous Poster]

Re: PT 60\" Mower

Hey Hans -which mower do you have?

 

[bubenberg]

Re: PT 60\" Mower

i have all the mowers that go with the 400 series, and as of yesterday morning, when i had my last discussion with the pt people, there was no commercial mower for the this model mentioned.

the discussion points were as delineated before:

1. uneven ground difficulty to maintain tip speed,
2. failure of the roller bearings
3. tightening of the belt: not enough or too much
4. i informed them that i would mount a 17 hp motor on my 60" fine cut mower. they in turn shared the problems not having a clutch when starting their test model with it's own motor. i let them know that the kunz acrease only had a clutch on their rough cut mower.

so, this is something new about a commercial mower for the 400 series.

 

[Anonymous Poster]

Re: PT 60\" Mower

I am wrong - I guess it is only for the larger unit - but why could you not use it - just change the plate and use a smaller displacement hydraulic motor - vs the one on it for 12 gpm

I have not had any problems with my deck and it seems to have plenty of power and speed - but again I only used it over the summer on my lawn - not commercially where constant heat and use factor in

I was cutting my lawn with a commercial Buton walk behind which I bought brand new - and I liked it - I have a very dense blue grass lawn - i really think that the PT deck actually cuts nicer and has more power - i could really bog down the Buton 14 hp in high grass - but the PT went right through anything with the thin really sharp blades

I'm surprised you have problems with tip speed

Need to check out my belts now that you mention it

 

[Anonymous Poster]

Re: PT 60\" Mower

Hans -explain the performance problem to me - re tipspeed
because this does surprise me - I didn't notice performance problems at all - and believe me I ran this straight up hills at 20 degrees which is the limit of the tractor - now I climb slow - but the mower seemed fine - the tractor wheel motors and trans pump need more power if your going to mow these kind of slopes all the time -

but again - I not really concerned about speed and I'm sure the performance would be different for me if i had it out every day beating it up in hot weather

 

[bubenberg]

Re: PT 60\" Mower

<font color=green>explain the performance problem to me - re tipspeed</font color=green>

tipspeed is what you should, would like to have your blades rpms to be.

you will see if you read the recent postings of Charlie and if i am not mistaking even Sedgewood are hinting that they could use some more umpf when mowing on an inclination.

as i indicated i am by no means changing to a bigger machine, because that uses more power to operate to get the optimum tipspeed wanted.

commercially or not commercially mowing is not the problem, the problem is more power when mowing on an incline with another 700 pounds of mowers dragging behind. in this situation is, where eventually i loose my ground and subsequently my tipspeed of my blades.

contrary to you i have several ztrs, that way out perform the pt 400 in constant tipspeed, quality of mowing, and ground speed. but they are not warranted to pull 700 pounds of other mowing equipment behind.

ergo, i am butting a 17 hp motor on my pt 60" finish mower, that way the "green machine" has do what it is best at crawling the hills and gullys, without getting stuck (pushing the converted pt mower and pulling the two 57" acrease). the ztrs last fall did just that at the end of the season and more than once did i have to leave the jobsite to get the "green machine" to pull myself out of the mud.

mowing is one of the most demanding jobs a tractorlike vehicle can do. the trottle must be at top speed and to make a living it has to move around 6-10 miles per hour.

with our kuboto ztr (Z21D) we average around 8-9 miles per hour and have a very acceptable cutting and stripping performance. i don't need that ground speed with the green machine once i have independent power to the mower, since i either can mow 12 or 14 feet wide (depending if i use the 48" pt mower or the 60" pt mower up front).

 

[Sedgewood]

Re: PT 60

Hans: <font color=green>but they are not warranted to pull 700 pounds of other mowing equipment behind.</font color=green>

And, I'd wager, neither is the 425. That extra 700 pounds is certainly adding to the load on the hydraulics and I presume increasing the waste heat loads too. You're operating the whole system hard against its limits. Does PT express any concern about it?

Here's a data point for you: I found with the 1845 that when I came up against its 28-30 degree limit of straight up climb it didn't matter if the mower was running or not - it just wouldn't put out enough torque to pull the slope. Adding a separate mower motor might not improve your ground speed at all, and in fact might slow you down with its extra weight.

As far as spindle bearings go, can you retrofit heavier spindles? And btw, I broke a belt too - when the right side striping issue first showed up my first thought was that maybe one spindle was slipping so I tightened the belt a bit. Well it didn't last long after that! The replacement I have set a bit looser than intuition seems to demand and its working just fine so far though I'm well shy of your 300 hours mtbf.

Sedgewood

 

[bubenberg]

Re: PT 60

until i have your machine (model) we mow those hills you describe with our ztrs and hydro walkbehinds. as far as the extra weight, 1000 pounds is the pt accessed limit.

just to mention the power dump for the 400 series is rated at 1000 pounds.

but you know the story about the man that can move railroad cars with a ram. the 425 has no problem to move the mowers behind and as of this year on steeper slops we adopted a new way of walking. on the way up i shut off the pt front mower. so the weeks i mowed in that direction i had to change my stripping pattern for the total area a bit.

if you need any help plowing i am available ... i am not kidding!

hrl