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: John Deere 955 Auxiliary Hydraulics Installation

02-18-2011, 08:32 AM
John Deere 955 Compact Utility Tractor Auxiliary Hydraulics

John Deere provides the owners of their 955 Compact Utility Tractors (CUT) with an option to install the Auxiliary Hydraulics kit. This kit pictured below does not include a lot of parts, but does take some time to install. This Tech Exchange will not only describe the steps to install this kit in detail, but will also provide some high resolution pictures from an installation on an actual JD 955. This installation took me just over 4 hours.

Since the John Deere 955 CUT operates with an open center hydraulic system, to utilize external valves or hydraulic equipment means that we have to install a diverter plug and the hoses to redirect the pressurized fluid and the return fluid from and to the Selective Control Valve (SCV). This kit will extend the Auxiliary Hydraulics to the rear of the JD 955. From this location the user has the option of installing hydraulic accessories such as backhoes, log splitters, additional control valves, etc. For my tractor, I have purchased a Woods Backhoe and wanted the option of being able to run the backhoe from the tractor hydraulics instead of the PTO Driven Hydraulic Pump that was supplied.

Let's begin the installation by verifying that we have all of the parts necessary to complete the installation:

1 - Hydraulic Hose
1 - Female Quick Attach Coupler
1 - Male Quick Attach Coupler
1 - Hydraulic Tube (Supply)
1 - Hydraulic Tube (Return)
1 - Bracket with decals installed
1 - Snap Ring (For Female Coupler)
2 - O-Rings (R26375 or Equivalent)
2 - O-Rings (R26448 or Equivalent)
3 - O-Rings (T77857 or Equivalent)
1 - Bulkhead Nut and Washer
1 - Diverter Plug
2 - 90 degree Elbows

Some people have purchased the diverter plug directly from John Deere and then supplied their own parts to complete the installation. Had I known more about hydraulics and hydraulic fittings I may have chosen to do that as well, but the kit does provide everything in one package and put my tractor back into service very quickly.

I have broken this installation into the individual steps necessary to perform the installation.

Step 1: I would start by engaging the tractor brake, and blocking the wheels. As we are removing parts we may be moving gear selectors and we need to make sure our tractor does not run away.

The first step of this installation in removing the center panel. The John Deere instructions for this kit ask you to lower the mower deck height control prior to removing this plate, but I havenít found the value of this so far. It doesnít hurt to do it, but I leave that up to you. There are 4 - 6mm bolts that secure the center panel to the tractor as illustrated in the following picture. Using a 10mm socket remove the 4 bolts and carefully lift the panel from the tractor. It may be necessary to move the shift lever and the PTO Select lever to gain enough clearance to remove this panel.

Step 2: The next step involves removing the SCV Shield. Start by removing the control knobs on both the speed selector, and the PTO selector if you havenít already removed them while trying to remove the center shield. These knobs are screwed on and may be removed by turning them counter clockwise. The knobs are annotated in the following picture.

Inside each of the fenders there are two bolts that secure the SCV Shield to the tractor. Using a 10mm socket, remove the 2 bolts under each fender that secure the Shield as shown in the pictures below. Slide the shield forward to remove. You may have to move the selectors to clear the shield.

Step 3: Remove the seat by loosening and removing the 4 nuts as shown in the figure below. Once all the nuts have been removed, disconnect the wiring from the seat harness. Please take care when lifting the seat as your fingers can get pinched where the seat pivots. I have two very black fingernails that can attest to this pinch hazard.

Step 4: Now that we have the middle panels and the seat removed, we need to remove the fenders. Each of the fenders is attached the same way, and each has a wiring harness that needs to be unplugged. I would recommend unplugging the wiring harnesses first. The left fender harness is shown in the picture below.

To remove the right fender, in addition to the wiring harness you will also have to remove the rockshaft control lever as shown in the following picture. There are two bolts that secure the rockshaft control lever to the link on the transmission.

Step 5: With the harnesses and the Rockshaft Control Lever removed, we now remove all of the bolts securing the fenders to the tractor. The pictures below show the bolts that secure the fender to the tractor. There are six bolts under the fender and a flange bolt, nut and spacer that secure the fenders to the footrests.

NOTE: Start with the Flange Nut, Bolt and Spacer that secures the fender to the footrest. Failure to start with this bolt could result in bending this portion of the fender when the other bolts are removed.

Step 6: The front seat bracket is the next item to be removed from the tractor. To remove the seat bracket we need to disconnect the speed selector lever, the 4WD selection lever and the PTO selector lever as shown in the pictures below.

To keep the bolts and selector arms together you can run a pass of duct tape around them to keep the bolts and washers with the arms. After unbolting the selector arms you just need to move them aside and then remove the jam nut and the adjustment nut from the top of the seat lockout linkage. This will allow you to raise the front seat bracket off the tractor. You may have to wiggle the front seat bracket a little or even nudge a hydraulic line a little to get the bracket off the tractor.

Step 7: We actually start the installation of the Auxiliary Hydraulics kit now with the removal of the pipe plug from the SCV and the installation of the diverter plug. The picture below shows the plug that needs to be removed. Remove this pipe plug, but do not discard. Install the diverter plug into this same hole until it bottoms out. You will note that the diverter plug is smaller than the pipe plug removed, this is because inside of the SCV are smaller threads specifically designed for this diverter plug installation.

You will then apply a sealant to the original pipe plug that was removed and re-install it into its original location.

You will note that in the above picture the Selective Control Valve (SCV) linkage was removed because I needed to make some repairs. If your linkage is loose or needs to be lubricated, now is a good time to perform repairs and or maintenance. Note that it is not necessary to remove these parts to perform the installation.

Step 8: This step prepares the SCV for the installation of the new elbows. To install the elbows we will need to disconnect the rear tube fitting by loosening the tubing nut that is pictured below, loosen the fitting jam nut and pivot the fitting so that we have enough room to install the new 90 degree elbow fittings. Then we remove the plugs identified below being careful not to allow any debris to fall into the open holes.

To prepare for installing the new fittings you will run the jam nut on each fitting to the top of its threads closest to the elbow. Then you will install an O-Ring (R26488) on each elbow just below the jam nut. In my kit, the elbow fittings came with these O-Rings installed, so be sure to verify this first.

Step 9: Install the new fittings. The following picture shows the existing fitting turned to provide enough clearance for the installation of the new fittings and the new fittings installed. When installing the new fittings make sure that you point them towards the rear of the tractor but do not tighten any of the jam nuts at this time.

At this time, you can turn the original elbow back to its original position and reinstall the tubing that you had removed to allow for the clearance to install the new elbow fittings. Once again, do not tighten any of the jam nuts just yet.

Step 10: Our next step is to prepare for and install the rear hydraulic tubes. I started this installation by preparing the rear bracket. The female quick coupler is held to the rear bracket using the circlip as illustrated in the kit of parts. Insert the female quick coupler though the plate from the label side, and secure using the circlip on the back side of the plate as shown in the following picture.

Once you have the circlip installed, we need to remove the top two bolts and lock washers from the top link bracket on the rear of the transmission as shown in the picture below.

Loosely install the new rear plate on the top link bracket with the label facing the rear of the tractor. Do not tighten the bolts as we still have to install the new tubing and we may need to adjust the plate to get the tubes in place.

Prior to placing the tubes in place we need to prepare the new elbow fittings for the tubes by installing an O-Ring (T77857) on each of the new fittings as shown below.

Now we can place the new tubes onto the tractor and route them according to the following picture. Snug the tubing nuts onto the elbow fittings, but do not tighten the nuts at this time. Note that I have one wire bundle on top of the left tube. I later rerouted this wire bundle to be under the tube.

Step 11: Now that we have the preliminary routing done, we need to install the O-Ring that seals the left rube against the female quick coupler. The following picture shows the installation of O-Ring (R26375) on the left tube.

Install the left tube into the female quick couple and insert the right tube through the rear bracket at this time. Install the bulkhead washer and nut on the right tube and snug them.

Step 12: At this point I started tightening everything up in the following order.

Tighten the bolts for the rear bracket.
Tighten the nut on the right tube. Be sure to hold the tube in position and keep it from rotating.
Tighten the female quick coupling onto the left tube, again ensure the tube does not rotate.
Tighten the jam nuts for the new elbow fittings
Tighten the tubing nuts at the new elbow fittings
Tighten the jam nut for the old elbow fitting
Tighten the tubing nut for the old elbow fitting

Step 13: We are almost at the point where we can start the tractor and check for leaks, but we first have to install the bypass hose. We start by installing the O-Ring (T77857) into the fitting for the right tube, and onto this fitting we install the tubing nut from the tubing nut end of the bypass hose.

Install the bypass hose onto the right rubbing fitting and tighten down. You will then install an O-Ring (R26375) onto the male end of the hose and then install the male quick coupler fitting. Tighten both of these fittings and insert the male end of the quick coupler into the female fitting.

The following picture shows the completed installation of the bypass hose.

Step 14: At this point we are ready to test for leaks. Since we may have had to move gear selector levers and controls we need to pay careful attention to the following steps to ensure our safety and the safety of our tractor.

LOCK the parking brake.

ENSURE that the transmission selector lever is in Neutral.
Start the engine and check all fittings for leaks, if there are any leaks stop the tractor and fix them before proceeding.

Using an adjustable wrench, move the rockshaft control lever and ensure that the left arms move according to the movement of the lever.

To ensure that the diverter plug is working properly, we will now disconnect the male quick coupler from the female and attempt to move the rockshaft again. The rockshaft should not move with the hose disconnected. If it does, the diverter plug has not been installed properly. Review the pictures and steps again to ensure that you have completed the installation according to these instructions.

If all has gone well, the only thing remaining is to reassemble our tractor. That can be done by reversing the steps for removing the seat brackets and control levers, then the fenders, the seat and finally the center plates.

I hope you have enjoyed this technical article, and if you have any comments or suggestions I would be delighted to hear them.

[Ed. Note: Please send questions or feedback directly to the author via PM.]