Mowing PT 60" Mower

Schultz · Jan 9, 2003

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 · Jan 9, 2003

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 · Jan 10, 2003

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 · Jan 11, 2003

Re: PT 60\" Mower

Hey Hans -which mower do you have?

bubenberg · Jan 11, 2003

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 · Jan 11, 2003

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 · Jan 11, 2003

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 · Jan 12, 2003

Re: PT 60\" Mower

explain the performance problem to me - re tipspeed

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 · Jan 12, 2003

Re: PT 60

Hans: but they are not warranted to pull 700 pounds of other mowing equipment behind.

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 · Jan 12, 2003

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

marrt · Jan 12, 2003

Re: PT 60\" Mower

 they in turn shared the problems not having a clutch when starting their test model with it's own motor. 

Han, from this comment, I assume the factory has been testing a wing mower? I often wondered why PT doesn’t produce a wing mower (they make every other attachment after all). I would like to get a wing mower, but I still think the professional ones like you use are too expensive for my use. Would be great if the factory decided to make one at an affordable price.

With regard to adding an engine to the PT mower, I have considered this idea as well. Don’t take offense, but for me, each hour I spend mowing is a wasted hour that I could use doing something else. I don’t like mowing and want to get it over with as quickly as possible.

It seems like an easy exercise to test whether adding an engine to the PT mower will significantly increase your ground speed. Just have someone time you going up a hill using the PT mower on. Then add 120 lbs or so weight, and take the same hill with the PT mower off. Should get you pretty close. I don’t know what kind of load the PT mower puts on the PT engine, but it must be significant.

Anonymous Poster · Jan 12, 2003

Re: PT 60\" Mower

RE - your post

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.

I know what tip speed is - and I know why it is important in maintaining cut quality

Was only inquiring - because I have not had this specific issue
- I also have not been dragging around two additional 60 inch mowers behind - so it does not surpirse me that you are having these issues and I would be surpirsed if simply adding an engine to the PT deck would solve your problem - Sounds like way too much for the unit - be interested to see the outcome

I understand that mowing is probably the most demanding use - and there IS a very big difference in using a unit commercially -

i also was not suggesting that the large ZTR would mow faster etc - just that the PT had more deck power vs the 14hp Buton and that the cut with both blades razor sharp was just as good or better on the PT - I mow no more than 4hrs without sharpening the blades

If quality mowing, though, is what I need a machine for - RE 95-99% of the hours - I don't think the PT is a good choice for many many reasons -

Look at the large golf course commercial units by Jac, Toro - etc - with wings etc to cut 12 or 14 ft - they try and keep weight down and the speed and hp to the deck way up
- just a different application

Well good luck - I really hope the it works

bubenberg · Jan 12, 2003

Re: PT 60\" Mower

Look at the large golf course commercial units by Jac, Toro - etc - with wings etc to cut 12 or 14 ft - they try and keep weight down and the speed and hp to the deck way up
- just a different application 

i think you are not quite right on the wing mowers you quote above. they are heavy and very costly and can't be used like our set up when the ground get's very wet.

those are the reasons why some 600 mowing hours i went with this less costly solution ... and now i am only improving on the existing rig .... that is all.

please look at these pictures and imagine the 400 with it's own mower (in the near future with it's own engine) and two commercial 57" acrease out to the rear left.

have a nice Sunday

hrl

MossRoad · Jan 12, 2003

Re: PT 60\" Mower

Hans,
Why don't you just give up the PT mower deck and tow(or push) another Acrease? Just asking /w3tcompact/icons/smile.gif

bubenberg · Jan 12, 2003

Re: PT 60

the cost of another acrease is way more than what i will spent on installing all the modifications on the pt mower. another aspect is the acrease are built a slant and the makes it harder to push and turn. but i have tried because each of them have a pt q/a plate welded on for easy loading and unloading. but based on your suggestion i will try some more ... thank you for the encouragement.

Sedgewood · Jan 13, 2003

Re: PT 60

Hans, here's a variant - put an adapter plate on a crossbar with an acrease at each end and pull two up front where you can see them and tow a third behind.

bubenberg · Jan 13, 2003

Re: PT 60

Sedgwood, we (Francis my mechanic/inventor/welder and I) have found out that pushing mowers is harder than pulling. the only reason to have a mower up front is to get under bushes, make a cleaner pattern at the edge of the area to be mowed. otherwise i would, as quit a few of you suggested, pull them all behind.

one thing you got to remember is the weight of the 1050 pounds is only at the start up, and since i put larger tires on the acrease the rolling of the mowers is a cake walk. to quote Chris Ashbury, the former VP of Sales and Son in Law of the owner of pt, mowing is the hardest thing you will ever do, the biggest power drain on a motor which powers a hydraulic system.

ergo, i am now testing the hypothesis: adding an engine to the front mower should reduce the power drain from the pt motor, since the only thing it has to provide is an optimum ground speed.

one option is to pull all the mowers behind the pt, but as i said the edges of a mowing area are going to be traveled over more often each week (compactation etc). if pulling all three mowers behind works better, that solves one thing, the chaffing coming into the motor area of the pt is going to be less (i hope, depending on the prevailing wind).

bubenberg · Jan 13, 2003

Re: PT 60

Hans, from this comment, I assume the factory has been testing a wing mower? I often wondered why PT doesn’t produce a wing mower (they make every other attachment after all)

as far as i know from my conversations with Chris and Terry, that was not a wing mower they were testing. they powered the 60 inch finish mower and run into problems not having a clutch to engage the belt which powers the blades. the acrease, other than the roughcut mowers, don't have a clutch and Francis and i are going to copy their setup for the 60" pt finish mower conversion.

Sedgewood · Jan 13, 2003

Re: PT 60

hans: have found out that pushing mowers is harder than pulling

actually what I envisioned was the wing mowers trailing off the ends of the transverse boom if that might make a difference.

i am now testing the hypothesis: adding an engine to the front mower should reduce the power drain from the pt motor, since the only thing it has to provide is an optimum ground speed. 

This presumes that the ground speed loss is from a horsepower limit rather than a wheel motor torque limit. My uphill experience seems to indicate I reach the wheel motor torque limit before loosing rpm ie: disconnecting the mower doesnt help. I recommend a test run with the mower off before you spend too much time on the conversion, unless of course like me ya just gotta do it anyway */

Sedgewood

bubenberg · Jan 13, 2003

Re: PT 60

i am only using this rig for mowing large areas not exceeding around 15% slopes (guestimate ain't got the tiltmeter) . for the steeper portions i turn my ztrs and hydro walkbehinds loose.

here is an example 1.8 miles of driveway on a 185 acre estate. we have to mow 40 feet wide around the total property and on both side of the drive way. this is an excellent assignment/example for pt/acrease hook-up. another property is 11 acres (my ex ... non paying .... no alimoney .... no child support ... no messing around ..... just a nice guy) and a 20 acre horse farm. before the acrease hook-up we were very tired doing these large properties. today they can be done with a three man crew in one day including trimming.