Yanmar's optional Power Steering Kit

[rScotty]

Originally Posted by richriddle
The YM276D in the barn has great power steering for those folks talking about power steering.



That's interesting. Do you have a picture of the power steering? I'd like to know what kind it is.
rScotty
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Back in the late 1970s and early 1980s when the US Yanmars were being sold in the US, locally, one of the knocks against all the competing compact tractors was the lack of power steering. There were several QA type loaders available from Yanmar for all the models from the YM135 to the YM336. These were nlce heavy powerful loaders that made steering with a bucket load an exercise in brute force. The only model with power steering was theYM336 - which came standard with a really fine factory power steering that ran off a large internal pump and flow divider on the starboard side of the engine block.

Late in the game, Yanmar brought out an add-on power steering kit for the YM180 series and larger. It was complicated, expensive, finicky to install, and tended to leak - but it made Yanmar the only compact on the market with power steering.
Here is a copy of the Advertising Brochure for the Power Steering kit. The tractor appears to be a YM226D. If one of these kits comes your way, better grab it regardless of condition.
rScotty

 

[marksold187]

My 187d was equipped with the factory optional power steering kit. Owner worked for a dealer and so I have the factory installation instructions as well. At some point in tractors life cylinder must have leaked and it was removed and hoses bypassed. Recently Hoye started selling a kit and the cylinder/valve separately. I got just the cylinder/valve. Valve is about mid way down the cylinder unlike factory n which was at the far end. Other than shortening the pushrod from the factory steering kit and drilling one hole larger on the frame bracket it worked. For anyone wanting info let me know . (FYI their website says it has 3/4 “ hole and flare fittings. Mine showed up with 18mm and SAE.

 

[Gjamtrac]

The picture on the literature is of the P/S kit made by Modular Controls (long since out of business). It was oval shaped. It was a pretty good system but the control valve was quite rough and wore out the O-rings causing it to leak out of the weep hole, and the O-ring had to be replaced fairly often. When disassembling the valve, it should be honed out so it is smooth. It was made in the US and uses SAE O-rings.
After Modular Controls went out of business Yanmar had DuBro build their P/S kits, which were round, but they discontinued production of the P/S kits due to lack of orders and I think the business was eventually sold to another corporation.

 

[California]

Mine has the leaky O-ring. It seems the little nut to remove the control valve, requires that the large nut on the primary cylinder be removed first, due to interference. How the heck do you hold the whole PS assembly secure enough to unscrew those two nuts, without distorting the aluminum? I gave up when I couldn't get anything apart using substantial force.

Any advice?

 

[marksold187]

This is what was in the manual from my tractor.

 

[rScotty]

Mark, thanks for taking the time to post those photos of Yanmar's optional power steering installation. I've always been curious about the history and continuing adventures of Yanmar's power steering.

BTW, the artwork in those pictures is really exceptional; they are an inspiration.
rScotty

 

[winston1]

Just for thought. I consider those power assist and no doubt Yanmar installed. However, the steering wheel unit is what I really call factory power steering. Don't think any American sold had these but numerous greys did.

 

[Gjamtrac]

The US model YM336 used almost the exact same steering column system for power steering.

 

[California]

My 187d was equipped with the factory optional power steering kit. Owner worked for a dealer and so I have the factory installation instructions as well. At some point in tractors life cylinder must have leaked and it was removed and hoses bypassed. Recently Hoye started selling a kit and the cylinder/valve separately. I got just the cylinder/valve. Valve is about mid way down the cylinder unlike factory n which was at the far end. Other than shortening the pushrod from the factory steering kit and drilling one hole larger on the frame bracket it worked. For anyone wanting info let me know . (FYI their website says it has 3/4 hole and flare fittings. Mine showed up with 18mm and SAE.

Interesting. You have the later system built by DuPro, see Gjamtrac's description of the difference, above.

It seems the Modular Controls version with the little control cylinder on top of the primary cylinder is what is on most YM186's, then around the time YM186 was superceded by YM187/YM180, the dealers started using the DuPro kit.

The Modular Controls owner/service manual has been posted here previously but your post of the DuPro manual is the first time that manual has been seen here - I think. Thanks!

Here's the Modular Controls version on my YM186D with it's inner tube 'diaper' to prevent drips from going upward to make a mess on the side of the hood.

As I noted, I tried to disassemble the unit to replace the O-ring in that upper control cylinder but couldn't find a way to hold that irreplaceable aluminum casting securely without risking crushing and distorting it.

 

[winston1]

The US model YM336 used almost the exact same steering column system for power steering.

Didn't know that, learned something new today.