standclear
New member
How easy should it be to turn on grass with hydrostatic drive? I bought a 1970 Foremost Sure Go recently and turning it on gravel is fine but the motor bogs down when i try to turn on grass.
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Hard To Turn On Grass???
- Thread starter standclear
- Start date
Alaska Snow Cat
Member
Well it depends as there are a lot of factors involved in any track rigs turning ability and a few that are unique to hydrostatic models. I have quite a bit of experience in the Thiokol/LMC 3700, Pisten Bullys and all sorts of excavators,dozers and skid steers which all have the hydrostatic drive so I'll give you my 2 cents worth.
One thing to keep in mind is your Sure Go was made when hydrostatic transmission technology was fairly new and a lot has been improved on since. The set up you have is probably meant to be driven by setting the throttle at it's best torque RPM and then engaging the steering levers to control direction and speed. This is the way most mechanical systems are designed and then there is usually a gas pedal to keep the RPMs up when the engine starts to bog down. If you ask the engine to do more work than it is capable of then it will bog down and may even quit which is called over stroking the pump. It is very easy to do. Most modern hydrostatics machines have some sort of processor/computer that prevents that from happening by de-stroking the pump automatically to match engine RPM to input controls by the operator.
Depending on the grass, track width, grouser depth, track tension, engine HP/Torque, condition of the drivetrain components and the type of turn you are attempting will all affect how how "easy" any tracked vehicle will turn.
As capable as the Ford 300 is, I would guess it is just a little under powered for the machine. Hydrostatics are not as efficient as direct drive at delivering power to the tracks and most modern snowcats that have hydrostatic drive have a big diesel engine to make up for that fact.
From what you described in the other post about what you have done to the Sure Go so far, I would not be so concerned about the hydrostatics but would be looking at all the other components that are drive train related. I see you went through the carb but how are the points,plugs, timing? How about compression, valve train etc? How about wheel bearings, gear boxes, track tension, chains. These will all affect performance. Also as old as the technology is on your rig, plus the with the power plant it has, I would not expect it to turn on a dime in all conditions.
Please keep us updated on how it all goes!
One thing to keep in mind is your Sure Go was made when hydrostatic transmission technology was fairly new and a lot has been improved on since. The set up you have is probably meant to be driven by setting the throttle at it's best torque RPM and then engaging the steering levers to control direction and speed. This is the way most mechanical systems are designed and then there is usually a gas pedal to keep the RPMs up when the engine starts to bog down. If you ask the engine to do more work than it is capable of then it will bog down and may even quit which is called over stroking the pump. It is very easy to do. Most modern hydrostatics machines have some sort of processor/computer that prevents that from happening by de-stroking the pump automatically to match engine RPM to input controls by the operator.
Depending on the grass, track width, grouser depth, track tension, engine HP/Torque, condition of the drivetrain components and the type of turn you are attempting will all affect how how "easy" any tracked vehicle will turn.
As capable as the Ford 300 is, I would guess it is just a little under powered for the machine. Hydrostatics are not as efficient as direct drive at delivering power to the tracks and most modern snowcats that have hydrostatic drive have a big diesel engine to make up for that fact.
From what you described in the other post about what you have done to the Sure Go so far, I would not be so concerned about the hydrostatics but would be looking at all the other components that are drive train related. I see you went through the carb but how are the points,plugs, timing? How about compression, valve train etc? How about wheel bearings, gear boxes, track tension, chains. These will all affect performance. Also as old as the technology is on your rig, plus the with the power plant it has, I would not expect it to turn on a dime in all conditions.
Please keep us updated on how it all goes!
standclear
New member
Thank you for your quick reply. I did cap, rotor, plug wires, points and condenser. Did a compression test on the motor, the lowest was 130 psi and the highest was 150 psi. The chains to the drive spocket are a little loose, I don't know how tight the tracks should be. The only thing that I can think of is that the filters for the hydraulic system is on the suction line and not on the return line like they should be, so the hydraulic motors are not reaching their full potential. So I was looking into putting the filters on the return line and installing a 100 mesh suction line strainer inside of the hydraulic tank to get better flow.
Alaska Snow Cat
Member
Not sure about your installation but the sunstrand transmissions I am familiar with have the main filters installed on the suction side of the pumps. You should be able to test the pressure of the pumps to determine the health of the pumps and their components.
northeastheavy
New member
Like Pixie my BR60+ does not have hydrostatic drive, but I drove around the fields and it handled fine. I know my grousers are 1/2 worn!! Could your grousers be digging in so much you are losing alot of power, where on snow you are not??? I would also think the larger and heavier the machine, like pixie said, probably the harder to turn on soft ground, combined with the loss of some power with the hydro drive??. Just my 2 cents worth!!!
300 H and H
Bronze Member
northeastheavy,
Your mechanical system is much more efficient than a hydro. Couple this with a strong little turbo diesel, and this is why you can turn on grass.
Wish our club could purchase your BR60+, but our machines are state owned, and they can only buy new machines, from what I have been told.
Regards, Kirk
Your mechanical system is much more efficient than a hydro. Couple this with a strong little turbo diesel, and this is why you can turn on grass.
Wish our club could purchase your BR60+, but our machines are state owned, and they can only buy new machines, from what I have been told.
Regards, Kirk
northeastheavy
New member
That makes sense!! Br60+ is surely a big difference from my old snow trac. New units with hydro and large engines to make up for the power loss must be nice to drive though???? Not to mention 4-5 foot wide tracks. That Foremost Sure Go does look heavy.
standclear
New member
The spec that I got from Foremost says it weight 2940lbs with the ford V4-91ci engine, two man cab, and no hydrostatic drive.
northeastheavy
New member
Wow!! Thats pretty light!! The BR60+ is 6000.pounds!!