This saga started way back in November of 2018 when the ring gear came off the flywheel: https://casecoltingersoll.com/showthread.php/81995-CCK-in-646-tossed-the-Ring-Gear-off-FLywheel
So, we towed the tractor into the garage and since we were pulling the engine off any way, we might as well:
1. Replace the Air sucking pump: https://casecoltingersoll.com/showthread.php/68618-Tiny-Bubbles-Hydraulic-suction-Line-leaking-air
2. Repair the Steering Sector gear : https://casecoltingersoll.com/showthread.php/83021-73-646-Steering-Sector-gear-and-shaft-repairs
3. Repair the loader valve: https://casecoltingersoll.com/showthread.php/82375-Fixing-Leaking-Loader-control-Valve-on-646
3. Add a Pto and Extra remote https://casecoltingersoll.com/showthread.php/83451-PTO-valve-amp-3-point-using-a-TCV-on-646
4. Add a Holding valve
5 Add power steering.
The thread will focus mainly on the power steering mod - install. One of my main things while doing this was to keep the modifications, hacking, of the tractor to a minimum. Maybe someday someone will restore it..
Plus this is essentially a prototype, if this Power Steering does not work, I have to be able to return the tractor to normal operation. So I did not modify many of the factory parts, at least not in a way that would prevent me from returning the tractor to normal operations. As it stands I should only need to re-install both factory Tie Rods and re-route the P/S oil supply to drain and the tractor will operate as before.
I have been thinking about or planning this upgrade since the discussions started on the forum back in January of 2017 in this thread. https://casecoltingersoll.com/showthread.php/54306-Loader-steering-cylinder-measurements We all tossed out many different ideas and requirements, and that discussion helped me break the process of adding power steering down into 3 areas: Hydraulic Supply, P/S Control Valve, and Hydraulic Cylinder.
One of the primary issues with adding P/S to a 646 or 644, is the need for a separate hydraulic flow for the power steering system. Case - Ingersoll used a couple of different methods over the years to accomplish this. The 648's started out with the power steering controller in the 'power beyond' line that eventually fed the loader. Which led to the P/S on that model being described a Quirky, because the P/S impacted the loader and the loader impacted the P/S
The 60xx and 7020 use a dual pump arrangement or effectively 2 separate pumps, one pump drives the PTO, and traction and a smaller pump drives the power steering and loader (also the backhoe if I recall correctly)
On the 40xx tractors Ingersoll used a hydraulic splitter valve, or more correctly a hydraulic Priority DIVIDER valve, Which is necessary to split one hydraulic supply into two different flows, and continue to provide flow to the 'priority' side when the rest of the tractor's hydraulic circuits are idle.
Consider that when the tractor is setting in neutral, the travel control is not in forward or reverse, there is little if any restrictions to the oil flow, so the oil runs around the system freely and at very low pressure.
If we simply Teed off part of that flow for the power steering, the oil, like water in a river, will follow the path of least resistance and run through the traction part of the system and not the P/S control, which means we won't get any flow or pressure for our power steering circuit.
Therefore we need a "priority divider valve" to create and maintain the separate flow for the P/S. A priority Divider valve has a hydraulic spool valve inside that makes sure the 'priority' flow port always gets 1.5 Gallons of oil per minute. Regardless of what the pressure in either side of the system is, you always get 1.5 GPM on the priority port.
Which is good and not so great.. Good in that the P/S circuit ALWAYS gets 1.5 GPM. So the steering speed and response is always the same no matter whether the engine is at Idle or WOT.
The possible BAD of a priority divider valve is that when the steering hits the stops, the valve will still try to push 1.5 GPM to the "priority flow" until something blows and in effect Deadhead the pump. The priority divider will attempt to divert all of the oil to the 'priority' circuit in order to get 1.5 GPM to go out that port.
That's why there HAS to be a relief valve in the P/S circuit, the particular valve I used has a relief valve built in. (Prince RD 405 R: http://www.princehyd.com/Portals/0/valves/valvesrd400.pdf ) If you use a different valve remember to add a relief valve that is plumbed back to the drain - tank in the P/S circuit somewhere..
Its good to note that the other port on a Divider valve is labeled EXCESS flow.. Basically if we don't need the flow of oil to make the 1.5 GPM for P/S, then its 'excess' flow and the Divider valve sends the oil out the 'excess' port, a better label might be MAIN flow.. .
The not so great of a Priority valve is that the P/S ALWAYS gets 1.5 GPM before the rest of the tractor gets any oil. You could say that when you are not steering, you're dumping 1.5 GPM of pump output to the drain.. And you are..
When I looked at replacing the hydraulic pump as part of this upgrade I installed a 0.73 Cu In pump (A 646, has a 0.55 Cu In (8.5 GPM) pump originally.. The new 0.73 pump, at WOT, should move 11.4 GPM, which is a tad much for a "16.5 HP" Onan CCKa to pull.
But the engine is not producing 11.4 GPM at 2200 - 2400 PSI.. Its producing 9.9 GPM at 2200 - 2400 PSI and 1.5 GPM at 1000 - 1500 PSI which it can handle. And, I get 9.9 GPM (instead of 8.5 GPM) for the tractor and loader.. (I find it fascinating that the 644 and the 648 were upgraded to a 9.5 GPM pump, but the 646 was forever left at 8.5 GPM)
The new pump bolted right up to the existing mount, and used the same Lovejoy coupler.
The new pumps output is the same SAE #10 sized port as the old pump. Both of the in - out ports are located in the center of the pump's body instead of the rear http://www.dynamicfc.com/documents/2016DynamicFullCatalog_Pumps_F20.pdf
The new pump has a standard SAE #12 port for the input - suction line. To get the suction line attached, I used a 45 Degree SAE #12 to 1" hose barb fitting, (# 4603-16-12 ) which is necessary to make the connection to the suction line without major kinks in the line.
The other fun part of the suction line on a 646A, is that the space between the engine's base - oil pan and the frame is SOO tight you cannot run a rubber suction hose through there.. I don't know HOW they accomplished that on the 648's. I had to re-use the OEM steel suction line.. Which had already been brazed up from rubbing on the OEM drain line.. To ensure that the line was not sucking air, I gave all the worn areas a good cleaning and externally applied a layer of JB Weld.
To create the necessary 2 hydraulic flows or Circuits, I ran the output of the pump first to the Divider valve, then the 'excess' port of the divider valve connects where the pump used to go. (More or less, I added a PTO valve to this tractor at the same time, so the output actually goes from the Divider to the PTO valve, then back to the TCV where the pump used to be connected.)
I installed the Divider valve between the tractor frame rails below and behind the engine, basically where the mid lift used to be and I reused 2 of the midlift mounting holes. Which puts the Divider valve in front of the steering gear.
(Which now all said and done a better location might have been on the inside of the right hand frame rail. The placement I used, across the frame rails right behind the engine prevents you from reaching in behind the engine from the left side.. Which makes hooking up the engine wiring a challenge.)
I only needed an 18 inch hose to get from the new pump to the input port on the Divider valve. The PITA of this brand - model of valve, IMO, is that ALL of the connections to it are pipe threads (NPT) which means you tighten the fittings, and use a hydraulic thread sealer, but you could wind up with the fitting pointing the wrong way. I got spoiled by the SAE - O ring fittings that I can align as I want and then tighten the nut - washer - O ring to seal it..
I opted for JIC #10 fittings on the Divider valves in and Excess - out ports to match the existing tractor fittings, and a JIC # 6 for the P/S - Priority flow. The input on the Divider is on one side and the outputs, both P/S - Priority flow, and Main - Excess flow are on the other side - bottom. http://www.princehyd.com/Portals/0/valves/valvesrd400.pdf
Another challenge of splitting the oil supply is that you need to route the output - drain of the P/S controller AND the output of the Pressure Relief both back to the tank. I guess one could go ******* and run the drains back to the tank filler cap….
But with a new pump and new P/S system on the tractor, I really wanted a Hydraulic oil filter in the system, and for that to be effective the filter needs to be in the return - drain line. It needs to filter ALL of the oil that is returned to the tank.. Therefore the drain from the P/S circuit needs to be plumbed into the drain BEFORE the filter.
This was a challenging part of the system to design and implement. By having a ~ 12 GPM pump I needed a filter that could handle that flow, which based on price and availability, it rounds up to a 25 GPM filter. https://www.surpluscenter.com/Brand...ga-Return-Line-Filter-25-PSI-Bypass-9-059.axd
Which is a BIG filter, not super huge, but real-estate on a 646A in the Drain line area is at a premium. AND, there are these pesky front tires that take up alot of the space where I thought I could put the filter.
The 'drains' starting at the P/S controller is a JIC # 6, and the priority valve's built in relief is a 3/8 NTP, so I Teed the output from the P/S controller in with the relief and routed both back to the main drain - return line. Which is where the fun started.
The standard drain setup on a 646A is a 5/8 ID steel from the TCV and a 5/8 steel line from the Loader valve that both arrive at a JIC #12 TEE fitting located on the right side of the 'engine compartment' below the loader valve, behind the engine (again). The 3rd leg of the tee normally connects to an additional 5/8 steel line that routes around the side of the engine and ends near the oil cooler in the front of the tractor.
The JIC # 12 Tee seemed the best place to route the P/S drain back into the system before the hydraulic filter. I was determined to not modify - hack the OEM return line, but instead replace that section of line from the JIC # 12 Tee to the cooler with the filter and something else..
The space between the CCKa's oil pan foot and the frame rail where the drain TEE is at is VERY tight, so much so that only a 5/8 Steel line could make its way out of there. My ¾ ID rubber return hose was not going to fit, nor would it make the bends needed.
Between the motor mounts, plus where the front wheel sits during a right turn and the size of the filter, the only practical place to locate the filter is right under the engine's oil drain plug. Butted up against the frame. The only way to connect to the filter in that location is come THROUGH the frame:
Therefore, I had to hack my tractor. There is now a 1 ¼ inch hole in the plate on front of the right side 'loader tower', similar to where - how the steering tie rod comes through the frame on the left side of the tractor. A carbon steel hole saw can and will make the hole. It takes time and lots of cutting Oil, but it can be done.
I wound up 'turning' the JIC # 12 TEE connector so that the 'open' end that used to connect with the steel line around the engine and forward to the oil cooler, is now pointing down instead of forward. Because the hydraulic filter is ¾ NPT, (did I happen to say I HATE NPT fitting in a hydraulic system?)
I was able to source a JIC # 12 Female to ¾ NPT 90 degree elbow (# 6501-12-12) which when attached to the JIC # 12 Tee put the ¾ pipe in a good position to attach the filter head. I added a ¾ NPT TEE to the 6501-12-12 fitting so I could combine the drain from the P/S circuit, then a 4" long pipe nipple runs through the hole I cut in the frame to the filter head.
The assembly OUTSIDE the tractor looks like this.
This can only be assembled in place, and I had to screw the filter head onto the pipe nipple before I connected the JIC #12 fitting to get this in place. Needless to say, it's a tight fit.
The output - Drain of the P/S controller, runs to a JIC # 6 to NPT fitting at the Priority Valve, then combined with the relief valve output, that runs through a 3/8" ID JIC # 6 hose and terminates at the ¾" NPT TEE in the drain line..
The last connection from the Hydraulic filter output to the Oil cooler is done with ¾ ID rubber drain line and hose barbs. To reduce the number of bends in the Rubber drain hose, I added another 4" long 3/4" pipe to the filter output, then a 45 Degree elbow puts the hose barb in about the best (not ideal) location to connect to the oil cooler. My only fear is that rubber hose might collapse or kink when hot. But it's where I can keep an eye on it. So we shall see.
PhotoAlbum: https://photos.app.goo.gl/1fbGxQfyTfoFVLku8
So, we towed the tractor into the garage and since we were pulling the engine off any way, we might as well:
1. Replace the Air sucking pump: https://casecoltingersoll.com/showthread.php/68618-Tiny-Bubbles-Hydraulic-suction-Line-leaking-air
2. Repair the Steering Sector gear : https://casecoltingersoll.com/showthread.php/83021-73-646-Steering-Sector-gear-and-shaft-repairs
3. Repair the loader valve: https://casecoltingersoll.com/showthread.php/82375-Fixing-Leaking-Loader-control-Valve-on-646
3. Add a Pto and Extra remote https://casecoltingersoll.com/showthread.php/83451-PTO-valve-amp-3-point-using-a-TCV-on-646
4. Add a Holding valve
5 Add power steering.
The thread will focus mainly on the power steering mod - install. One of my main things while doing this was to keep the modifications, hacking, of the tractor to a minimum. Maybe someday someone will restore it..
Plus this is essentially a prototype, if this Power Steering does not work, I have to be able to return the tractor to normal operation. So I did not modify many of the factory parts, at least not in a way that would prevent me from returning the tractor to normal operations. As it stands I should only need to re-install both factory Tie Rods and re-route the P/S oil supply to drain and the tractor will operate as before.
I have been thinking about or planning this upgrade since the discussions started on the forum back in January of 2017 in this thread. https://casecoltingersoll.com/showthread.php/54306-Loader-steering-cylinder-measurements We all tossed out many different ideas and requirements, and that discussion helped me break the process of adding power steering down into 3 areas: Hydraulic Supply, P/S Control Valve, and Hydraulic Cylinder.
One of the primary issues with adding P/S to a 646 or 644, is the need for a separate hydraulic flow for the power steering system. Case - Ingersoll used a couple of different methods over the years to accomplish this. The 648's started out with the power steering controller in the 'power beyond' line that eventually fed the loader. Which led to the P/S on that model being described a Quirky, because the P/S impacted the loader and the loader impacted the P/S
The 60xx and 7020 use a dual pump arrangement or effectively 2 separate pumps, one pump drives the PTO, and traction and a smaller pump drives the power steering and loader (also the backhoe if I recall correctly)
On the 40xx tractors Ingersoll used a hydraulic splitter valve, or more correctly a hydraulic Priority DIVIDER valve, Which is necessary to split one hydraulic supply into two different flows, and continue to provide flow to the 'priority' side when the rest of the tractor's hydraulic circuits are idle.
Consider that when the tractor is setting in neutral, the travel control is not in forward or reverse, there is little if any restrictions to the oil flow, so the oil runs around the system freely and at very low pressure.
If we simply Teed off part of that flow for the power steering, the oil, like water in a river, will follow the path of least resistance and run through the traction part of the system and not the P/S control, which means we won't get any flow or pressure for our power steering circuit.
Therefore we need a "priority divider valve" to create and maintain the separate flow for the P/S. A priority Divider valve has a hydraulic spool valve inside that makes sure the 'priority' flow port always gets 1.5 Gallons of oil per minute. Regardless of what the pressure in either side of the system is, you always get 1.5 GPM on the priority port.
Which is good and not so great.. Good in that the P/S circuit ALWAYS gets 1.5 GPM. So the steering speed and response is always the same no matter whether the engine is at Idle or WOT.
The possible BAD of a priority divider valve is that when the steering hits the stops, the valve will still try to push 1.5 GPM to the "priority flow" until something blows and in effect Deadhead the pump. The priority divider will attempt to divert all of the oil to the 'priority' circuit in order to get 1.5 GPM to go out that port.
That's why there HAS to be a relief valve in the P/S circuit, the particular valve I used has a relief valve built in. (Prince RD 405 R: http://www.princehyd.com/Portals/0/valves/valvesrd400.pdf ) If you use a different valve remember to add a relief valve that is plumbed back to the drain - tank in the P/S circuit somewhere..
Its good to note that the other port on a Divider valve is labeled EXCESS flow.. Basically if we don't need the flow of oil to make the 1.5 GPM for P/S, then its 'excess' flow and the Divider valve sends the oil out the 'excess' port, a better label might be MAIN flow.. .
The not so great of a Priority valve is that the P/S ALWAYS gets 1.5 GPM before the rest of the tractor gets any oil. You could say that when you are not steering, you're dumping 1.5 GPM of pump output to the drain.. And you are..
When I looked at replacing the hydraulic pump as part of this upgrade I installed a 0.73 Cu In pump (A 646, has a 0.55 Cu In (8.5 GPM) pump originally.. The new 0.73 pump, at WOT, should move 11.4 GPM, which is a tad much for a "16.5 HP" Onan CCKa to pull.
But the engine is not producing 11.4 GPM at 2200 - 2400 PSI.. Its producing 9.9 GPM at 2200 - 2400 PSI and 1.5 GPM at 1000 - 1500 PSI which it can handle. And, I get 9.9 GPM (instead of 8.5 GPM) for the tractor and loader.. (I find it fascinating that the 644 and the 648 were upgraded to a 9.5 GPM pump, but the 646 was forever left at 8.5 GPM)
The new pump bolted right up to the existing mount, and used the same Lovejoy coupler.

The new pumps output is the same SAE #10 sized port as the old pump. Both of the in - out ports are located in the center of the pump's body instead of the rear http://www.dynamicfc.com/documents/2016DynamicFullCatalog_Pumps_F20.pdf
The new pump has a standard SAE #12 port for the input - suction line. To get the suction line attached, I used a 45 Degree SAE #12 to 1" hose barb fitting, (# 4603-16-12 ) which is necessary to make the connection to the suction line without major kinks in the line.
The other fun part of the suction line on a 646A, is that the space between the engine's base - oil pan and the frame is SOO tight you cannot run a rubber suction hose through there.. I don't know HOW they accomplished that on the 648's. I had to re-use the OEM steel suction line.. Which had already been brazed up from rubbing on the OEM drain line.. To ensure that the line was not sucking air, I gave all the worn areas a good cleaning and externally applied a layer of JB Weld.
To create the necessary 2 hydraulic flows or Circuits, I ran the output of the pump first to the Divider valve, then the 'excess' port of the divider valve connects where the pump used to go. (More or less, I added a PTO valve to this tractor at the same time, so the output actually goes from the Divider to the PTO valve, then back to the TCV where the pump used to be connected.)
I installed the Divider valve between the tractor frame rails below and behind the engine, basically where the mid lift used to be and I reused 2 of the midlift mounting holes. Which puts the Divider valve in front of the steering gear.
(Which now all said and done a better location might have been on the inside of the right hand frame rail. The placement I used, across the frame rails right behind the engine prevents you from reaching in behind the engine from the left side.. Which makes hooking up the engine wiring a challenge.)
I only needed an 18 inch hose to get from the new pump to the input port on the Divider valve. The PITA of this brand - model of valve, IMO, is that ALL of the connections to it are pipe threads (NPT) which means you tighten the fittings, and use a hydraulic thread sealer, but you could wind up with the fitting pointing the wrong way. I got spoiled by the SAE - O ring fittings that I can align as I want and then tighten the nut - washer - O ring to seal it..
I opted for JIC #10 fittings on the Divider valves in and Excess - out ports to match the existing tractor fittings, and a JIC # 6 for the P/S - Priority flow. The input on the Divider is on one side and the outputs, both P/S - Priority flow, and Main - Excess flow are on the other side - bottom. http://www.princehyd.com/Portals/0/valves/valvesrd400.pdf

Another challenge of splitting the oil supply is that you need to route the output - drain of the P/S controller AND the output of the Pressure Relief both back to the tank. I guess one could go ******* and run the drains back to the tank filler cap….
But with a new pump and new P/S system on the tractor, I really wanted a Hydraulic oil filter in the system, and for that to be effective the filter needs to be in the return - drain line. It needs to filter ALL of the oil that is returned to the tank.. Therefore the drain from the P/S circuit needs to be plumbed into the drain BEFORE the filter.
This was a challenging part of the system to design and implement. By having a ~ 12 GPM pump I needed a filter that could handle that flow, which based on price and availability, it rounds up to a 25 GPM filter. https://www.surpluscenter.com/Brand...ga-Return-Line-Filter-25-PSI-Bypass-9-059.axd
Which is a BIG filter, not super huge, but real-estate on a 646A in the Drain line area is at a premium. AND, there are these pesky front tires that take up alot of the space where I thought I could put the filter.
The 'drains' starting at the P/S controller is a JIC # 6, and the priority valve's built in relief is a 3/8 NTP, so I Teed the output from the P/S controller in with the relief and routed both back to the main drain - return line. Which is where the fun started.
The standard drain setup on a 646A is a 5/8 ID steel from the TCV and a 5/8 steel line from the Loader valve that both arrive at a JIC #12 TEE fitting located on the right side of the 'engine compartment' below the loader valve, behind the engine (again). The 3rd leg of the tee normally connects to an additional 5/8 steel line that routes around the side of the engine and ends near the oil cooler in the front of the tractor.
The JIC # 12 Tee seemed the best place to route the P/S drain back into the system before the hydraulic filter. I was determined to not modify - hack the OEM return line, but instead replace that section of line from the JIC # 12 Tee to the cooler with the filter and something else..
The space between the CCKa's oil pan foot and the frame rail where the drain TEE is at is VERY tight, so much so that only a 5/8 Steel line could make its way out of there. My ¾ ID rubber return hose was not going to fit, nor would it make the bends needed.
Between the motor mounts, plus where the front wheel sits during a right turn and the size of the filter, the only practical place to locate the filter is right under the engine's oil drain plug. Butted up against the frame. The only way to connect to the filter in that location is come THROUGH the frame:

Therefore, I had to hack my tractor. There is now a 1 ¼ inch hole in the plate on front of the right side 'loader tower', similar to where - how the steering tie rod comes through the frame on the left side of the tractor. A carbon steel hole saw can and will make the hole. It takes time and lots of cutting Oil, but it can be done.
I wound up 'turning' the JIC # 12 TEE connector so that the 'open' end that used to connect with the steel line around the engine and forward to the oil cooler, is now pointing down instead of forward. Because the hydraulic filter is ¾ NPT, (did I happen to say I HATE NPT fitting in a hydraulic system?)
I was able to source a JIC # 12 Female to ¾ NPT 90 degree elbow (# 6501-12-12) which when attached to the JIC # 12 Tee put the ¾ pipe in a good position to attach the filter head. I added a ¾ NPT TEE to the 6501-12-12 fitting so I could combine the drain from the P/S circuit, then a 4" long pipe nipple runs through the hole I cut in the frame to the filter head.
The assembly OUTSIDE the tractor looks like this.

This can only be assembled in place, and I had to screw the filter head onto the pipe nipple before I connected the JIC #12 fitting to get this in place. Needless to say, it's a tight fit.
The output - Drain of the P/S controller, runs to a JIC # 6 to NPT fitting at the Priority Valve, then combined with the relief valve output, that runs through a 3/8" ID JIC # 6 hose and terminates at the ¾" NPT TEE in the drain line..
The last connection from the Hydraulic filter output to the Oil cooler is done with ¾ ID rubber drain line and hose barbs. To reduce the number of bends in the Rubber drain hose, I added another 4" long 3/4" pipe to the filter output, then a 45 Degree elbow puts the hose barb in about the best (not ideal) location to connect to the oil cooler. My only fear is that rubber hose might collapse or kink when hot. But it's where I can keep an eye on it. So we shall see.

PhotoAlbum: https://photos.app.goo.gl/1fbGxQfyTfoFVLku8