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Discussion Starter · #1 ·
I've posted this picture earlier on introductions sub-forum to find out what would be the correct sub-forum for my project. I'm not sure if my small tractor should be called sub-compact or garden tractor, but decided this home-made forum is the most appropriate place for my thread. I'll explain the reasons later.

Our family of four is living in countryside and use the tractor mainly for snow removal with plough, scoop and blower in winter and minor earth moving and grading in summer.

The tractor is a Lokari Horse, which was designed and made in Finland in 80's. It has 0.95 liter 22 hp Misubushi L3E diesel engine, hydraulic AWD with hub motors and a capable hydraulics for front and rear mounted equipment. As the license plate may tell, it is road legal, but with 10 km/h (6 mph) top speed it's not very attempting to drive even to the gas station.
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My tractor is of the first and in many ways preliminary series of that tractor. It has many questionable design solutions or even flaws, which were re-designed for later models. Even the manufacturer was admitting this later. This was the only tractor the Lokari-company ever made and even though the company is still existing, they can offer no spares or other support anymore. They are concentrating to their main and original business, producing fender liners and other moldings.

Vehicle Car Wheel Truck City car Vehicle Snow Snow blower Snowplow Car Vehicle Automotive tire Tire Auto part Automotive exterior

There are spares available for the engine, but all other main components are not supported by manufacturers anymore. Something can be found from ebay, but much need to be re-invented to keep it running and to improve the equipment. That's my justification to start the thread here at home made -sub-forum.

My tractor is currently under repair and some modification. Root cause to start the repair was a hydraulic oil leak. And due to the design it is not possible to replace the leaking connector without removing lots of other components and actually the whole hydraulic block. Also there are design-related problems in the steering joints and again getting hands on that requires lots of other stuff to be removed. The valve block for work hydraulics worn and leaking, and as there are no spares available anymore for that either, I'll replace it with a new and better one, which offers one more valve and some improved functions within the same space.

I have a scoop and a hydraulic driven snowblower, which I plan to mount on the rear, but I need to construct the mounting equipment for those. And I'll modify the cab with a new hatch and to have the rear window opening. And as final touch, I'll improve the work lighting to get full coverage around the tractor and to be seen when plowing snow on our yard road junction to the highway.
 

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Very neat tractor. I like the protectors on the rims for the valve stems.
 

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That's cool!
 

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That's a neat little thing.
I had one of those mini-Mitsubishi engines, I bough it new to power an AC unit on a camper I had.
Loud, and bullet proof.
 

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Discussion Starter · #6 · (Edited)
Those protectors for tire filling valves are actually threaded. You could screw a plug to cover it. I may look suitable plastic plugs, just need to find out the thread size.

After removing the work hydraulics valve block the pumps can be seen very well. On top right there is the flywheel housing, then to the left variable displacement drive hydraulics pump and then fixed displacement work hydraulics pump. The inlet pipe for the work hydraulics pump is original, although it certainly doesn't look like factory made. The spring in the middle is just stored there temporarily.

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In the hunt for the hydraulics' leaks we ended up to lifting the engine and connected pumps up. When the powerpack is away I will make some openings to the bottom plate for future repair and maintenance.
 

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Those protectors for tire filling valves are actually threaded. You could screw a plug to cover it. I may look suitable plastic plugs, just need to find out the thread size.

After removing the work hydraulics valve block the pumps can be seen very well. On top right there is the flywheel housing, then to the left variable displacement drive hydraulics pump and then fixed displacement work hydraulics pump. The inlet pipe for the work hydraulics pump is original, although it certainly doesn't look like factory made. The spring in the middle is just stored there temporarily.

View attachment 2475405

In the hunt for the hydraulics' leaks we ended up to lifting the engine and connected pumps up. When the powerpack is away I will make some openings to the bottom plate for future repair and maintenance.
Interesting front pump. Adjustment on left looks like a compensator. Could be a vane pump or radial piston like an Eaton model 12. I'm guessing spring compensated vane. Does outlet of front pump go to directional control valve, or straight to motor?
 

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Discussion Starter · #8 · (Edited)
Front pump i.e. drive hydraulics pump is a variable displacement radial axial piston pump Danfoss VPA 20 MS. It's mechanically controlled, the control rod of the pump is connected to the two-end-pedal (can be seen in front of the pumps), which is used to adjust tractor speed and direction. Outlets (one for forwad and other for rearwards) of the pump goes to drive hydraulics block, which devides the flow parallel to all four hub motors. The block is also equipped with a flow devider valve acting as a sort of diff lock.

edit: pump type corrected
 

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Discussion Starter · #9 ·
I ended up to ordering an Italian Salami VDM6 5-valve monoblock for the work hydraulics. It had suitable dimensions, connections, flow rating and good selection of functions. I needed floating positions for front and rear mount up/down cylinders' valves as well as free spooling middle position for hydraulic motor valve. The two remaining valves are for regular 2-way cylinders.

There are also other valves with similar spec, but that Salami was available in reasonable price and quick delivery from Finland. For example German Bucher HDM11 would also be a suitable monoblock valve, but it would have taken two to three months to get it and it's 30 % more expensive.
 

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It sounds like you know your way around hydraulic systems.
I recently bought a new control block from Flowfit UK; just a simple thing for auxiliaries, but their price's are really good.
 

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Discussion Starter · #11 ·
I've also got many recommendations about Flowfit UK. To be honest I forgot to check their prices and offerings regarding this valve block. But on the other hand, I supported a local company.

I am in no way an expert on hydraulic systems. Due to my profession and personal interest I've learned some general things about designing hydraulic systems on vehicles, but I have zero experience on practical assembly or repair work. Yet.
 

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I'm still figuring it out as well.
One difficulty is the huge range of couplings and fittings. When you can walk into a shop with a sample it's not too bad, but when you mail order things it's hard to know which one will fit. aside from different threads, you have male or female cone, or flange, or tapered threads. Metric and inch threads, flared metal tubes, etc.
My tractor has 2 different ones and both are hard or impossible to find.
Since I have a lathe, I can just make fittings I need. But I wonder how aggravating, time consuming, and expensive it would be otherwise.
The local tractor repair shop up the road from me can make hoses and their prices are very good, so that's a real help.
In your pictures things don't look too rusty; so hopefully you won't need a lot of new parts.
 

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Discussion Starter · #13 ·
The excessive oil leak has protected from the rust. 😁 There is some rust in the front end of the frame, but the steel is so thick, that the rust is only a visual defect.

Biggest thing that may need new parts is the steering. The original design is rather peculiar and questionable from durability point of view, so if its too worn, it needs complete re-design.

I can share your pain of different fittings. There are several different types of fitting in my tractor already from factory, and some others due to the repairs. Basically common types, but different threads may change the game. We'll see when going to shop for new hoses.

You are lucky to have the tools and skills to make the missing parts yourself! Luckily I too have a friend who has lathe and milling machine, and skills to manufacture parts. And I'm actually repairing my tractor on his workshop.
 

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Discussion Starter · #14 · (Edited)
I mentioned previously that the drive hydraulics pump is radial piston pump. That was a mistake, I didn't think enough before writing. Of course it is mechanically controlled variable displacement axial piston pump.

Now, there is a small leak in that drive hydraulics pump control rod feedthrough. I was trying to get a new seal and get my hydraulically minded friend to sort it out. But now it looks like the seal is not available anymore. Additionally there is a risk of some other problems due to the pump being not used for long time in past. Fortunately I found a workshop in western Finland specialized in overhaulig and repairing Danfoss VPA20 pumps and having large amount of disassembled pumps for spares. Therefore I ended up to taking the pump out and sending it to this specialist for maintenance. Sure it costs and takes some time, but then I can be sure that this critical main component will be fine for long time.
 

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Discussion Starter · #15 ·
The tractor is now very much disassembled. Now when the engine is removed you can see how much pipes and hoses are going under it. And there is no way getting anything done to them without removing the engine. Not very good design. Therefore I cut a roughly 8"x17" service opening on the frame under the engine for future service and repair, and a bolted steel plate to close it to prevent snow and mud getting in.

Next will be time to get hands on front axle and steering. An improved design for the king pin bearings is under work.

2480006
 

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Discussion Starter · #16 · (Edited)
My tractor has a very peculiar rack-and-pinion steering constructed inside the front axle beam. There is an input shaft going in to the beam in the center of the pivoting axle bearings. So the pinion is in the center of the axle beam, and there are two rack bars over and under the pinion moving opposite directions. That means that when the steering wheel is turned right, both racks bars are moving outwards. That is because the steering levers connecting the rack and the wheel hub are on different sides of the axle beam. Left one is on rear side and right one is on front side of the beam.
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I assume that construction is created to make it easy to change the track width. The axle beam consists of a bigger middle part and smaller rectangular hollow sections on both ends, which can be bolted on different track widths. In the picture left side is set for narrow track and right one for very wide track. Also the connections on the hydraulic hub motors are identical this way.

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I am not quite sure if that was the original construction for the king pin bearing, but it had slide bearing bushes for radial load and ball thrust bearings for axial load. Both were in pretty bad condition. Therefore I'm going to change the design so that I'll use two flanged slide bearing bushings taking care of both radial and axial loads. I'll also get my friend to lathe new king pins from high quality steel to get intact and durable sliding surfaces for the bearings and the tolerances optimized. I hope that will work well enough.

I know that opposed conical roller bearings would be the correct way to make it, but within the current bearing housings there is no space for such solution. That would require cutting of the existing bearing housings and making new, bigger ones for the roller bearings. So for now I'll give a try for the sliding bushings.
 

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Discussion Starter · #17 · (Edited)
The frame of this tractor has bolted front part, which holds the front axle and provides the mounting for the front mounted equipment. Now when the front part was cleaned and inspected, I found several ruptures or cracks, and some not-so-well made repairs. It seems that off-centerline impacts from the plough has loosened the mounting bolts and then, when the connection was loose, it has amplified impacts and caused the damage. One plate is easier to replace than repair, but most cracks needs to be opened partly with angle grinder and welded with high current to make sure the crack area is fully melted.

I try to take some pictures of the repairs.
 

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Discussion Starter · #19 · (Edited)
Yes, I think so too. But to be honest, it was the only way to get known defects repaired. But now I am happy, that the reparations will be made properly, and I know the weak points and I can use the tractor such manner, that excessive loading on weak points is avoided.

Between the steering wheel and front axle rack-and-pinion steering gear there are a double universal joints for turning the almost vertical steering shaft to a horizontal one. That has not been working properly, the steering force is uneven due to lousy support of the shafts and too big joint angles. I'm not sure if it would be good even with better support of the shafts, so I bought an used steering bevel box of Toyota Hiace. When it arrives, we'll see how it can be fitted into the limited space. It should be easier to mount properly and to eliminate the uneven steering force.

The drive hydraulics pump just arrived from overhaul. There was indeed a need for service and repair. Wear and tear over specs, and additionally some old repairs with improper parts, but that's all done now. It was a big cost, but still less than a new pump and it was necessary to get the tractor working properly for many years to come.

My biggest remaining worry is hub motors. There are absolutely no spares available for the motors any more. And no direct replacement. If any of them fails, all four has to be replaced with what is best adaptable to the design. This far they have shown no signs of leak and seem to provide sufficient torque, so I hope for the best.
 

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Discussion Starter · #20 ·
The front part of the frame is now repaired. Upper face plate is completely new and slightly improved design for better strength. There were multiple cracks not only on welds but also on the plates, which implies it to be something higher strength than regular mild steel. I was suspecting that already when making the service opening on the bottom of the frame and drilling holes for mounting bolts.
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The front axle and a repaired and painted front part is ready to be bolted to the main frame.
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I designed the improved king pins and my friend got them machined yesterday. Bigger thread on the right end is for mounting to the hub carrier and it will be tightened by a spanner wrench and secured with hard thread locking compound. The left side of the collar as well as the cylindrical smooth part are for slide bearings. The slot on the left end thread is for washer rotation preventing notch and a hole for a split pin.

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