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Discussion Starter · #1 ·
Interceptor posted this picture of the trans motor swash plate minimum displacement angle from 9° to 6°. What I don't know is how much shorter to make the spring retainer or whether one can be purchased outright from Sauer Danfoss. Any help?
 

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Discussion Starter · #4 ·
Yes a replacement minimum angle stop can be purchased to increase transmission speed. Send me an email for the PDF service instructions.
 

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Discussion Starter · #5 ·
K45 is the model number of the transmission motor, 0,1,6,7,8 and 9° minimum displacement stops are Avaialble for about $20. You need the motor number and model number to order a different minimum stop angle. Motor number 83020504. I have a 6° on the way. Your local Danfoss distributor can order you one today.
 

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Discussion Starter · #6 ·
The trans motor is basically a two speed and that is what we feel when we think the transmission shifts with the treadle pedal. Some work understanding the servo piston spring force is needed to make the motor transition from Max to minimum angle more smoothly. This will maintain power(torque) up through the engine RPMs.
 

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Did you get your 6 degree stop in yet? I wouldn't be surprised if you really bog the engine when it shifts. Mine works great but I'm turbocharged. I fooled around a little bit with the hydraulic motor shifting. I tried modulating the motor shift solenoid valve using a PWM controller/driver. It cannot me modulated, it's either on or off. The motor could possibly be modulated hydraulically by using a different type of valve, but it's not intended to operate that way, it is a two speed motor not a variable speed motor. The rate of transition can be changed by altering the orifice size on the shift line. I don't use high range anymore, it stays in low all the time and it's fast enough for my needs. jumped out the gearshift switch with a resistor to make the ECU think it's in high range all the time. I think the high range shift map works better with my combination of turbo, fixed command lever, and 6 degree motor stop and low range. I've been wanting to add a switch in line with the shift solenoid so I can prevent it from shifting. Sort of a low-low range for slow heavy work.
 

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Discussion Starter · #8 ·
Yes I do have the 6° stop, but have not installed as yet. To many issues to correct first lol. As you noted going there(6° stop) requires every bit of torque that engine can muster and a pump that is making all the flow it can. I have the engine about right now, but the pump pintle lever is not taking the swash plate to max angle because the forward throttle cable is too short.

You are right, the on off solenoid does not have a magnetic flux path that is conducive to power stepping response. The combination of spring rate, hydraulic force and orificing can dampen the swash plate movement between high and low motor speed(old school propotional response) but my calculations show this to be most unlikely with the motor components, the orifice sizing and length are not possible without a reduction hydraulic force area. So I have abandoned that effort.

Been eyeing up a 7° or 8° stop as well, but keep me posted on your proportional effort, that has real promise if can be done! Controller logic and a ramp able current may be tough to get, but that's the ticket.

Thanks for all your help Interceptor!
 

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Discussion Starter · #9 ·
I just reread your post Interceptor, a line orifice may be just the ticket. Happen to know what size that orifice diameter is? Probably in the valve block, but right before the servo cavity would be ideal.
 

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It's been quite a while since I've been actively working on it, all my notes and docs are on an old laptop that I don't use anymore, I'll have to dig that stuff up. I think the motor doc for the K45 from Sauer Danfoss describes the use of an orifice in the shift port to adjust the rate of shift.
 

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Here is the description of operation from the technical manual for the motor.

"L and K Frame variable motors are designed to operate in two positions: maximum and
minimum displacement. The motors are spring biased to maximum displacement and
hydraulically shifted to minimum displacement. SAE-B mount motors can operate with a
single or dual line control. Cartridge mount motors operate with a single line control only.
Pressure applied at port X1 shifts the motor to minimum displacement. Pressure at X2 (dual
line control) can assist the shift to maximum displacement. Refer to the table above for
control input pressure range.
Control orificing
Cartridge and SAE mount motor controls rely on external valving and orificing to
regulate shift speeds. You can achieve quick acceleration (shift to min) and slow
deceleration (shift to max) simply by installing an orifice in the tank line of the external
control valve.
SAE-B mount motors with single line controls can have optional, internal, supply and
drain orifices installed to regulate control response times. Contact your Sauer-Danfoss
representative for available orifice sizes."

The motor in Brutus is single line control with no internal orifices. The hydraulic schematic does not show an orifice in the control valve either.
In the service manual I found this:
"The two speed manifold modifies pressure and flow to the
shift plate in the pump motor depending on selected gear
and speed. There are two distinctive ramps per drive gear.
The two speed manifold should be tested for proper
operation using Digital Wrench®. Go to the Special Tests
menu - Output State Control and select Command a Duty
Cycle."
The words ramp and duty cycle lead me to believe that the solenoid valve is being modulated. I tried ramping the coil current from 0 to 100% over 10 seconds and it still resulted in a near instant motor shift. It's possible that the pressure does ramp but the motor doesn't begin to shift until a certain pressure threshold is reached and then it shifts to full stop. I didn't dig any deeper because it just wasn't that important to me. I'm more interested in backshifting the valve/motor in response to load.
 

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I've been watching for a deal on a suitable replacement motor and finally found one. This new motor is a two speed axial piston motor like the stock one, but it has a larger displacement and has external adjustments for minimum and maximum displacement limits. At the factory settings it provides 10% increased starting torque (for accelerating from a stop, pulling a load, etc.), 41% increased high speed torque (for maintaining speed up hills, etc.), and 29% reduction in maximum speed. I've had it installed in my Brutus for two weeks now and I'm very happy with the results. I can now maintain 18 MPH in high range up a steep hill where it struggled to do 10 MPH with the stock motor. High range maximum speed is 23.5 MPH and low range is 10.6 MPH, with adjustment it can reach 29 high and 13 low with 14% increased torque over stock.
The motor is a Bondioli & Pavesi M4MV50-5-/31. Surplus Center has a few of them in stock for $220 which is an amazing deal, these normally cost several thousand. Unfortunately it's not a direct bolt-in swap. It did require extensive modification to the pump command lever for clearance, and about $100 in hoses and fittings.
 

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I'm not sure what you're asking for. There is no adjustment on the stock motor, you need to take it apart and replace the internal stop with a different part. The docs are available from Danfoss.
 

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Just trying to achieve the happy medium with forward speed and with set up on command lever and squash plate......for pulling hills and would be happy with 25 mph......slow off the line.....feels like its struggling to get moving in high range with no load
 

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Do all of the hydrostatic drive adjustments in the order listed in the manual (neutral position adjustment, travel cable adjustment, engine speed cable adjustment). Then start with the HP spring adjustment bolt fully tight. If the engine bogs down or cannot maintain RPM under load, loosen up on the HP spring until you get the performance you want. I prefer to err on the side of too tight. Don't expect too much.
 

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I will give it a shot.....like I said just looking for better response @ take off in high range and better hill climbing empty,for most of my work I will be in low range anyway.......just want better take off in high.....like it struggles to get going......that problem is that a norm cararistic of it?.to bad they didn't have a mid range like kubota.....anyway I will let you know how I make out. Thanks again,all and any help on dialing this in is greatly appreciate.
 
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