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View Full Version : Which way on a hill is worst on the hydro system??


johnwon
06-11-2007, 06:59 PM
Does anyone know which is worst for the pumps and wheel motors....going straight up and down a hill or mowing across, or diagonal where you are mowing up and across at the same time. Thanks for any insight.

mkroher
06-11-2007, 07:42 PM
Straight up a hill is the worst.

But....straight up or diagonal on a slope is a lot safer than side to side. Well, with a ztr.


Also, doing a 180 at top speed in a driveway when striping a lawn... is also the worst thing you can do to the pumps. 3 pt turns, adds life to the pumps. Ask any dealer.

Scag48
06-11-2007, 08:21 PM
Doing 180's is not going to blow up the pumps. They will indefinately last forever if you change the oil regularly and as long as they don't leak you're fine. The pumps and motors are pretty simple pieces, there isn't anything very complicated in the system. I will agree that going uphill is hard on the pumps, the wheel motor couldn't care less though. The pump takes the brunt of that as it's trying push the mower up the hill with a fairly hefty load.

captken
06-11-2007, 09:01 PM
I don't think it makes a difference either way. I got over 3000+ hrs out of the Hustler Z I have before I had pump/motor problems. I replaced the left side, the right side went out soon after.

Hustler Z was new in 2001.

I don't think hills affected the pumps as much as the other stuff I used to do with a mower....pulling logs, pulling trailer loaded with logs, spiking the pumps using the mower in things other than it's intended purpose.

Check this out from 2005.

http://www.lawnsite.com/showthread.php?t=96772

I doubt any of you kiddies have done such a thing!

johnwon
06-11-2007, 10:06 PM
I don't think it makes a difference either way. I got over 3000+ hrs out of the Hustler Z I have before I had pump/motor problems. I replaced the left side, the right side went out soon after.

Hustler Z was new in 2001.

I don't think hills affected the pumps as much as the other stuff I used to do with a mower....pulling logs, pulling trailer loaded with logs, spiking the pumps using the mower in things other than it's intended purpose.

Check this out from 2005.

http://www.lawnsite.com/showthread.php?t=96772

I doubt any of you kiddies have done such a thing!
I remember seeing that pic......you must of had some real good ones.

johnwon
06-11-2007, 10:11 PM
I have read in some threads about some people mowing along the side of a hill where one wheel had most of the weight, and have them complain about a clicking or clattering sound. Anyway that didn't sound too good.

Richard Martin
06-12-2007, 05:03 AM
It shouldn't make any difference unless there is a problem with the bearings inside the wheel motor to begin with. There generally isn't a "up" side to hydro motors and pumps. Now if you're hydro tank is low on fluid and the system sucks air while it's on a hillside, that could trash the hydros.

lifetree
06-12-2007, 07:38 AM
I don't think hills affected the pumps as much as the other stuff I used to do with a mower....pulling logs, pulling trailer loaded with logs, spiking the pumps using the mower in things other than it's intended purpose.

Check this out from 2005.

http://www.lawnsite.com/showthread.php?t=96772

Captken -- That is extreme, I'm impressed ... what ZTR are you using now ?

Sammy
06-12-2007, 07:51 AM
Straight up a hill is the worst.

But....straight up or diagonal on a slope is a lot safer than side to side. Well, with a ztr.


Also, doing a 180 at top speed in a driveway when striping a lawn... is also the worst thing you can do to the pumps. 3 pt turns, adds life to the pumps. Ask any dealer.

Worst ? ...............

Pumper
06-12-2007, 11:32 AM
As far as the hill, going up at an angle puts the highest pressure to one wheel. When one wheel is "higher" than the other on the hill, the "lower" wheel carries most of the weight and has to do most of the work. You will get your highest pressure spike on the hill when you are going accross the face and try to turn uphill. One wheel is doing all of the work.

That being said, you will see spikes of close to 3,000 PSI. The pump is rated for 1000 PSI continuous and up to 3500 PSI peak (1% of the time).

The highest pressure spikes will come when the wheel is trying to move while being "held". This occurs when you hit a wall, hit a curb, hit anything that stops the momentum of the machine while you still have the levers pushed forward. You can see spikes well over 4,000 PSI. You will see close to this when you do 180's on blacktop just because of the traction you get on blacktop versus on grass. Wheel slip is the easiest way to handle pressure spikes.

ranger350
06-12-2007, 05:25 PM
It is very unlikely that you will damage the hydrualics. Simply put, If you exceed the pumps capacity it will go into relief, protecting the pump and motor/cylinder. Proper maintenance and clean oil is key to the longevity of hydraulic system.

lifetree
06-12-2007, 06:46 PM
It is very unlikely that you will damage the hydrualics. Simply put, If you exceed the pumps capacity it will go into relief, protecting the pump and motor/cylinder. Proper maintenance and clean oil is key to the longevity of hydraulic system.

Ranger350 -- Thank you for this clarification !!

johnwon
06-12-2007, 10:40 PM
Thanks to all who responded, it is good to know what not to do. Thanks again!!

captken
06-12-2007, 10:55 PM
Captken -- That is extreme, I'm impressed ... what ZTR are you using now ?

That same Hustler Z and an Exmark AS. The pumps and wheel motors are both new on the Hustler, and she is good to go.

Pumper
06-13-2007, 09:49 AM
Ranger350,

This would be true if the pumps had relief valves but they don't. The pumps used on commercial turf equipment are light duty (bantam duty) pumps. They do not have relief valves. Most have some sort of shock valve (if the equipment manufacturer pays the extra money for them) that helps to clip pressure spikes before they get too high. Hydro Gear has theirs set at 2900 PSI. But a shock valve will only bypass about 3-4 GPM whereas the pump can produce 9 GPM for a 10cc (BDP10) or more for the larger pumps. This plus the fact that you have to take into account the time it takes for the shock valve to open, you can still see spikes over 4000 PSI with a shock valve. Wheel slip was designed as the original pressure relief system.

Also, shock valves in the pumps only protect the pump. The spike is started in the motor and moves up the line to the pump before it is clipped. There is no protection for the motor but the motor can handle the spikes better than the pumps.

mrbobian
06-13-2007, 10:55 AM
Ranger350,

This would be true if the pumps had relief valves but they don't. The pumps used on commercial turf equipment are light duty (bantam duty) pumps. They do not have relief valves. Most have some sort of shock valve (if the equipment manufacturer pays the extra money for them) that helps to clip pressure spikes before they get too high. Hydro Gear has theirs set at 2900 PSI. But a shock valve will only bypass about 3-4 GPM whereas the pump can produce 9 GPM for a 10cc (BDP10) or more for the larger pumps. This plus the fact that you have to take into account the time it takes for the shock valve to open, you can still see spikes over 4000 PSI with a shock valve. Wheel slip was designed as the original pressure relief system.

Also, shock valves in the pumps only protect the pump. The spike is started in the motor and moves up the line to the pump before it is clipped. There is no protection for the motor but the motor can handle the spikes better than the pumps.

Wow... you really know your stuff, are you a dealer or mechanic or something? I am very impressed.

ranger350
06-13-2007, 01:27 PM
Lucky the 997 has one then :P

johnwon
06-13-2007, 09:00 PM
Thanks Pumper for sharing your knowledge on this subject, I do think a lot of people learn from you.

Pumper
06-14-2007, 10:06 AM
Thank you all for your comments. To be honest, I work for a supplier to the some of the equipment manufacturers. I moved to a different job within the company so I no longer work with any turf companies but I fell in love with the turf machines. They intrique me as to how they work. I still browse the websites and read up as much as I can. I try to offer information when I can but I do try to keep my personal beliefs on the machines to myself.

As for the 997, I apologize. I didn't realize Kanzaki had added a shock valve to their unit. This is a special unit they designed and built for John Deere with the pass through for the deck drive. I have seen it at shows but I really haven't ran the machine. Sorry.

razor1
06-14-2007, 10:43 AM
captken,
Have you sent that pic to Hustler? They might just put it on the wall at Hustler HQ. :drinkup:

Grass Man
06-14-2007, 01:43 PM
Pumper,
.... I am interested in your point of view. I don't know how qualified you are, but I would like to hear your point of view for a similar scenario about the KUBOTA ZD 28's or any of the ZD's since they are more Hydrostatic than Hydraulic? Am concerned more about longevity than anything else.
.... I realize this may be a tough scenario since it involves KUBOTA who appears to be VERY quiet and secretive concerning information and especially on these transmissions.

Thanks in advance

Grass Man


Ranger350,

This would be true if the pumps had relief valves but they don't. The pumps used on commercial turf equipment are light duty (bantam duty) pumps. They do not have relief valves. Most have some sort of shock valve (if the equipment manufacturer pays the extra money for them) that helps to clip pressure spikes before they get too high. Hydro Gear has theirs set at 2900 PSI. But a shock valve will only bypass about 3-4 GPM whereas the pump can produce 9 GPM for a 10cc (BDP10) or more for the larger pumps. This plus the fact that you have to take into account the time it takes for the shock valve to open, you can still see spikes over 4000 PSI with a shock valve. Wheel slip was designed as the original pressure relief system.

Also, shock valves in the pumps only protect the pump. The spike is started in the motor and moves up the line to the pump before it is clipped. There is no protection for the motor but the motor can handle the spikes better than the pumps.

razor1
06-14-2007, 02:12 PM
Grassman,

Since you mentioned Kubota. I had a ZD 21 with about 1000 hrs and the trans. went out. Kubota did fix it under warranty, they told me the early units were engineered wrong from the factory. Needless to say, I got rid of it soon after. Good Luck with that Kubota

johnwon
06-14-2007, 02:44 PM
Pumper, If you know how to answer this question....please do.
What is the difference between the Parker TG and the Parker TF wheel motors. I have seen where Gravely has used one or the other on a certain machine and then the next year change to the other??? This is done while still using the same size motor; like Parker TG 15ci then to Parker TF 15ci ??
Thanks if you can shed some light on this.

cybervision
06-14-2007, 03:59 PM
Here are the specs on the 2 motors:

TF series: http://www.parker.com/pumpmotor/cat/english/1590-007.pdf

TG series: http://www.parker.com/pumpmotor/cat/english/1590-009.pdf

The TG is a 3000/4000# extra heavy duty motor and the TF is a 2000/3000# motor.

I only glanced at this but the torque and speed appear to be the same at any give pressure and flow.

johnwon
06-14-2007, 05:54 PM
Here are the specs on the 2 motors:

TF series: http://www.parker.com/pumpmotor/cat/english/1590-007.pdf

TG series: http://www.parker.com/pumpmotor/cat/english/1590-009.pdf

The TG is a 3000/4000# extra heavy duty motor and the TF is a 2000/3000# motor.

I only glanced at this but the torque and speed appear to be the same at any give pressure and flow.
Thanks for your help on this....now I know.

Pumper
06-14-2007, 06:23 PM
Grassman,

Most commerical machines run one of two systems:

Split system - axial piston pump supplying flow and pressure to a low-speed/high-torque gerotor motor. For the "average" machine, the pumps are 10-14cc and the motors are 230-300cc (cubic centimeters). This gives you 10-12mph on a 1200 lbs machine with 24" wheels.

Integrated system - axial piston pump supplying flow and pressure to a high-speed/low-torque piston motor. The motor is connected to the output axle through gears. The gearing is normally 20:1. You end up with the same 200-300cc output that way.

The split system is a modular set up where you can easily change parts. You also have more options for motor and pump displacements.

The integrated system is more fixed and is not as easily serviced but it is cheaper to build.

Kubota has done a lot of things to help their system (spin on filters, steel gears, heavy duty bearings, etc.). They have really beefed up their transmissions from when they first introduced them. I really don't have much experience with the Kubota system. I have driven it at the Expo but I haven't mowed with it. Sorry.

Pumper
06-14-2007, 06:25 PM
Johnwon,

Just to add a little on the Parker motors, the TG is the big brother of the TF. They are very similiar but the TG has bigger bearings, a bigger internal shaft and has the option of a larger output shaft (1.5" versus the 1.25" of the TF). The TF is the most common in the Turf market. There are a few guys who are running the TG on their larger machines.

johnwon
06-14-2007, 11:14 PM
Johnwon,

Just to add a little on the Parker motors, the TG is the big brother of the TF. They are very similiar but the TG has bigger bearings, a bigger internal shaft and has the option of a larger output shaft (1.5" versus the 1.25" of the TF). The TF is the most common in the Turf market. There are a few guys who are running the TG on their larger machines.
Thanks for the info.....I guess I got fortunate with my 2006 Gravely 160XDZ
because they came with the TG unless the specifications were in error. I noticed that Gravely did away with the TG in all of their XDZ ZTRs for 2007.