Hydrostat question. Tires, too.

notjustair · May 26, 2015

As I was mowing today I got to wondering, on a small hydro (like ZTR size) does running slow heat the fluid up faster versus going fast? Clearly the load and amount of work is a defining factor, but if that is all equal which heats the fluid up more, full tilt or half speed?

Also, many moons ago I remember that Grasshopper brand mowers used a shallow lug ag type tire. Dos anyone have experience with them? With all of this rain I get stuck at least once each time I mow. My ZTR is set up just like a Grasshopper - deck, drive wheels, then a dolly wheel. I thought about switching to something like a shallow ag bar but I thought that might tear up the ground a lot on turns. These tires are fairly worn anyway, so I need to do something.

Can you tell I am bored and ready to get into the field - I am pondering the lawn mower!

Dick2 · May 27, 2015

Hydrostatic systems are designed to be operated at full engine speed, not at partial engine speed! The travel speed of the machine is controlled by the lever that changes the angle of the wankel plate, which how you are supposed to operate the machine.

FBH44 · May 27, 2015

I wanted Carlisle AG lug tires with the “TRU-POWER” tread on my Troy-Bilt lawn mower. I got a slightly diffferent Carlisle lug, I realized later, a more gentle tread. It still slips a little bit on steep hills. It is still a bar-type tread, looksl ike a tractor tread. But NO, it does not tear up sod or grass, I never notice it doing anything like that.

davediehl@hotmail.com · May 27, 2015

I have carlisle lug tires on all of my mowers. They don't tear up grass unless you spin them pulling. I loaded mine with antifreeze and water. Pulled my 18 foot bass boat around the yard with ease.

Geo-TH,In · May 27, 2015

My terramite is hydrostatic. The last time I changed my fluid, 300 hrs, it smelled burnt. So I installed an temp prob in the sump and installed an electric fan to blow air on the pump and torque motor. Terramite says their temps get around 200, mine stays under 150 until I was using it to climb hills. That shot the temp over 160 where my thermometer doesn't register.

So, I will say for me, it not the speed or how much I'm lifting or digging, it's how much load I put on the torque motor.

I go past the hydraulic repair shop almost everyday where I see ZTR ourside all the time. Last time I was there he was working on a twin engine dixie. I asked him what goes wrong with the ZTR's. He said pumps and motors, pumps and motors. Then I asked how many hours to they usually last? He says depends on operator and a few other things like how they take care of them, typically 1000-3000 hrs.

Now the hydrostatic unit on my JD275 is dripping on the garage floor. I need to remove it, split it apart and glue it back together with a flexible sealer. That will be a winter job. Hydrostatic units are nice but far from trouble free.

Eric in IL · May 27, 2015

I have a Grasshopper with the bar tires. If you turn with one tire stationary it will tear out grass. I have learned to keep both tires rotating during a turn.

NoNewParts · May 27, 2015

can't help you on the tires, I run ags on most everything.
clay, mud, snow here.
R-4's and turfs spin = more of a mess than cleats make

as said HST's need rpm to work properly.
keep the revs up and pick a gear range that lets you keep the go pedal to the floor.
Local Kubota mechanics I know say that is the number 1 problem with new HST owners. They lug around at low rpm in too high a gear range.

John M · May 27, 2015

Nah, wont hurt the hydros. I have one ZTR with over 600 hrs on the machine. It cuts fast in the front yard, slow in the back and the rest. Not super slow, but alot slower! Ive changed the fluid and filter on both of every 100 hours, and have never noticed a burnt smell, but there is some discoloration. For tires, I know they are a little spendy, but look at the tires for a Dixie Chopper and see if they come in your size.. They are specifically made for ZT mowers, have the "tractor lug" design, but dont tear up the yard in turns. (At least the one on both my mowers dont.

hd6gtom · May 27, 2015

I would run the tractor type rears on everything, but they are made in a limited number of sizes. I cant find them for the big mower.

notjustair · May 27, 2015

I run it at full throttle - I was referring to slow or fast speed. I don't understand hydros enough to know if they are gotten when you are creeping slower or hotter when you are running them at their maximum flow. All of this with the engine at rated rpm.

Good info on ag bar tires. It looks like they do no worse than the ones on there.

MARK ROBKE · May 27, 2015

I bought a used ztr that the previous owner had put ag/cleated tires on it.It is better going forward thru muddy spots,but when I make turns on normal dry yard conditions,the inside tire tends to slide,which makes the zero turn aspect difficult.I believe it is because the cleats are designed to have traction pulling but not holding back.I also believe the front axle should pivot to allow weight to rest equally on all 4 tires when on slightly uneven terrain;mine does not.As to your hydrostat,run at hi engine rpm,and then low ground speed should not matter.Mark

buickanddeere · May 27, 2015

Where does it say in the operator's manual to cut grass at less than full rated Rpms?
Why do you want to operate the machine at less than rated Rpms?

Geo-TH,In · May 27, 2015

The owner's manual on my terramite says to only run at speed, easier on the hydraulics.
I run at half to 2/3 and have 1600 hours on 20 hp kohler and the girl doesn't use a drop
of oil.

John M · May 27, 2015

I think hes talking about how fast the mower moves, not the speed of the engine.

Texasmark1 · May 27, 2015

I run all my air cooled engines where I want. Only engine I lost was a Kohler Courage and it was a casting design bracing (lack of) problem and lots of folks on here griped about them. Nothing wrong with the combustion chamber or it's parts.

On tires, I initially went to bar lugs which you can purchase as an alternate tire on some of the ZTs. I think Bad Boy is one of them. Reason was mowing the back side of my dam in the mornings when it's cool and the grass is wet. Slope is 25-30 degrees. Mower weighed about 1k# and liked to slide down hill even with the bar lugs. I bought some ATV snow studs and the performance is night and day. I have 3 of my mowers with them now and one is a spray machine with the deck removed and sprayer mounted on the rear behind the seat. On days like we have been having, I can go out in the pasture and run through mud and 3-4" standing water in pursuit of fire ants which are driven out of the ground by the saturated condition and nar once got stuck.

Google ATV snow studs.

DR. EVIL · May 27, 2015

Nobody's stated a brand or model of engine, but I've seen KOHLER advertising charts for the old cast iron
flat head K-series engines that show cooling air flow is DIRECTLY PROPORTIONAL to RPM. Means at 2700 rpm
they make 75% of the cooling air flow that they would make at 3600 rpm.

If an antiquated engine like that can perform to that level, a newer more modern engine should too.

The manual says run wide open because they are not buying the gas, and they can sell more rebuild parts
when you run them that hard. And if the cheap diecast conn rods fail, they for sure window the block!
More money from parts sales!

buickanddeere · May 27, 2015

(quoted from post at 17:56:43 05/27/15) Nobody's stated a brand or model of engine, but I've seen KOHLER advertising charts for the old cast iron
flat head K-series engines that show cooling air flow is DIRECTLY PROPORTIONAL to RPM. Means at 2700 rpm
they make 75% of the cooling air flow that they would make at 3600 rpm.

If an antiquated engine like that can perform to that level, a newer more modern engine should too.

The manual says run wide open because they are not buying the gas, and they can sell more rebuild parts
when you run them that hard. And if the cheap diecast conn rods fail, they for sure window the block!
More money from parts sales!

Engine fail because they are lugging under load. While operating too hot from reduced cooling airflow. The increased heat makes detonation/knock more likely which will break connecting rods.

D beatty · May 27, 2015

I just looked at the four manuals of my garden tractors ( 2 Briggs and 2 Kohlers and it says to run full throttle to get the best mowing job. But says nothing about that you can't run at 3/4 throttle. If the grass is not heavy I run at 3/4 throttle and if grass is heavy full throttle and how sharp your blades are has a lot to do with how much power you need . The engines never lug because the govenor will kick in. The one Briggs is an 18 HP opposed with over 1,600 hours on it and the other Briggs is a 20 Hp Vanguard with 400 hours. The two Kohlers are both pro seires V twins 22 HP and 24 HP 500 and 700 hours.

Texasmark1 · May 28, 2015

Google ATV tires and look up Snow Studs. I have them on 3 mowers, different sizes and they work great, for me better than bar lugs made for mowers. Largest size I have is 23x12x10, or 23x10x12, I forget which.

W_B · May 28, 2015

(quoted from post at 22:19:22 05/27/15) I run all my air cooled engines where I want. Only engine I lost was a Kohler Courage and it was a casting design bracing (lack of) problem and lots of folks on here griped about them. Nothing wrong with the combustion chamber or it's parts.

I think we were talking hydros, not engines. The hydro units I own have fans to cool the hydro unit so you need to keep the rpm up to keep the fan moving air over the unit. Every recommendation I've ever seen from actual users has been to keep rpm in the upper range and adjust your speed with the hydro control. Higher engine speed keeps that all important tip speed on the mower blades high enough to get a good cut.

GVSII · May 28, 2015

(quoted from post at 17:47:29 05/27/15) I just looked at the four manuals of my garden tractors ( 2 Briggs and 2 Kohlers and it says to run full throttle to get the best mowing job. But says nothing about that you can't run at 3/4 throttle. If the grass is not heavy I run at 3/4 throttle and if grass is heavy full throttle and how sharp your blades are has a lot to do with how much power you need . The engines never lug because the govenor will kick in. The one Briggs is an 18 HP opposed with over 1,600 hours on it and the other Briggs is a 20 Hp Vanguard with 400 hours. The two Kohlers are both pro seires V twins 22 HP and 24 HP 500 and 700 hours.

When mowing,I run about 3/4 throttle regardless of load.If the load is too much I drop down a gear.Whatever it takes.
The only things that run at top governor speed around here are the portable generator and the walk behind snow blower,neither of which have an operator controlled throttle.

D beatty · May 28, 2015

My neighbor bought a new Husquvarna 26 HP garden tractor and he went through 3 sets of deck belts first summer. The dealer sent service out a number of times and said they couldn't find anything wrong and put new belts on it.He ended up cutting throttle speed to 3/4 and took shields off over belt pulley and now has no problems with belts. The new snow blower that I bought last fall you can some what control the speed of engine. The throttle control has three settings idle,3/4 and full throttle.

DR. EVIL · May 28, 2015

Who the heck has said ANYTHING about an engine failure? Just you!

Trying to get that last cubic foot of cooling airflow by running
the engine so fast stresses the cheap diecast conn rod in those
old Kohler engines. Increasing engine speed from 3/4 to maximum
increases tension on rod 50%.

If the grass is so tall I need maximum HP to cut it I slow down!
My mower tractor is a hydro, I've got lots of slow speeds! If I
use anywhere close to full HP I smoke a $80 drive belt on the
mower!

Stick to giving advice on your Buicks & Deere's. You don't know
half of what you think you know about air cooled engines!

Texasmark1 · May 28, 2015

Well the engine comment that got me going is down below in this post. The remainder of the initial question was about tires. On the
question of hydros, per the original question, all of my mowers are hydros. Only had one failure in the last 15 years........the JD L110. It
blew a hydro because I was running at FULL THROTTLE, making sharp turns in the freshly cut grass in an effort to clean the mud off my
tires prior to shedding. The tranny didn't like that. Mfgr told me that the L110 had a low end pump and it had dino oil. The rest she
said used syn. They sent me the repair parts and a gimme cap. When I refilled it I filled it with Mobil 1. Still running and I use it daily.
Actually it's my Gator and it is usually at half or less speed.

buickanddeere · May 28, 2015

(quoted from post at 17:30:56 05/28/15) Who the heck has said ANYTHING about an engine failure? Just you!

Trying to get that last cubic foot of cooling airflow by running
the engine so fast stresses the cheap diecast conn rod in those
old Kohler engines. Increasing engine speed from 3/4 to maximum
increases tension on rod 50%.

If the grass is so tall I need maximum HP to cut it I slow down!
My mower tractor is a hydro, I've got lots of slow speeds! If I
use anywhere close to full HP I smoke a $80 drive belt on the
mower!

Stick to giving advice on your Buicks & Deere's. You don't know
half of what you think you know about air cooled engines!

I don't know what your news flash is. Of course anybody with half a brain slows down in heavy cutting.
Operating a machine at full load while operating at 3/4 rpm stresses it more than operating at 3/4 load at rated rpm.
The shaft torque and combustion chamber pressure is reduced.
Less tendency for the engine to detonate/knock which is rarely heard or noticed by the operators of equipment. Detonation is what breaks connecting rods and spins bearings besides running the engine low on oil.

Hydrostat question. Tires, too.

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