John Deere Powr-Trol

John Deere's Powr-Trol unit is an ingenious device that is relatively simple and tends to work very well. Far more information is available than can be relayed on one page. In fact, a whole web site could be devoted to just the Powr-Trol unit. But I will attempt to touch on some specific points that come up over and over again.

Here are a couple of pictures related specifically to the Powr-Trol plugs. The question was asked as to why the rocker arms would not move while a loader was being used on a tractor. The tractor had a Powr-Trol unit on it.

There are two sets of plugs (two plugs in each set) that are used with the Powr-Trol unit. Each set has a hole in the side (roughly 1/4" diameter) through which hydraulic fluid enters. One set of plugs has a solid front end and hollow back end to which hoses would be attached. The oil is directed to the rear. The other set of plugs have a hollow front end and a solid back end. The oil is directed internally.

Powr-Trol plugs<== On the left is a plug for use with the rockshaft arms. In the middle is a plug for use with an external hydraulic unit, such as a remote cylinder. On the right is a cap that can screw down over whatever plug is not being used, both to keep dirt from entering, and (in the case of hoses) to keep oil from leaking out. As you can see, I have not used the remote cylinder plugs for some time. I will be in the future, however.

Powr-Trol plug locationThere is a bracket attached to the Powr-Trol unit that can hold the set of plugs not currently in use. Here, the yellow arrows point to the remote cylinder plugs (not in use), and the blue arrows point to the rockshaft plugs (currently in use). ==>

It is generally assumed that all Powr-Trol units are identical, as they can generally be interchanged from tractor to tractor, even between different models. And while they are interchangable, they are not necessarily identical. Each Powr-Trol valve housing should have a serial number on it. This picture shows the serial tag on my Powr-Trol unit, number PCV-80821. When purchasing parts for your Powr-Trol, be sure you know your serial number.

One of the most common replacement parts needed for the Powr-Trol unit are new o-rings. As the old o-rings become worn, oil starts leaking around the plugs. When you go to purchase new o-rings, be sure you know the serial number of your Powr-Trol unit. This is one of those areas where not all Powr-Trol units are identical!

Early Powr-Trol units prior to PCV-67905 only have two-seals per plug - one small o-ring and a V-seal. Newer style units have three o-rings per plug. They can be replaced after simply removing the plug, but they are not easy to get to. I have attempted to take a picture down the plug hole and point out the location of the three o-rings.

John Deere has an excellent publication that you can purchase. It is number SM-2011. It has detailed explanations of how the Powr-Trol unit works, colored flow diagrams, and explains how to adjust and maintain your Powr-Trol unit. Everyone who owns a tractor with Powr-Trol should get one. To order yours, contact John Deere's Service Publications Department at 1-800-522-7448.

QUESTION: I can't get my Powr-Trol unit to work properly. The arms raise but don't stay up. I've been through everything and still can't seem to get it to work correctly. Any ideas?

ANSWER: Assuming you have the SM-2011 manual, let's just go back through the basics again. A faulty gasket or piston seal frequently causes this situation. The oil will go into the cylinder and raise the rockshaft, but the oil will not stay in place and "leaks out" somewhere.

1. If the gasket between the valve housing and the tractor rear housing is bad, oil can leak from the through a small cast opening in the bottom of the valve housing that the gasket covers. This does not require removal of the tractor rear housing to check.

2. If the leather cup (neoprene ring on later models) at the end of the piston is bad, oil will leak around (or through, if ripped) the cup once the rockshaft is raised. Leather cups should be soaked in oil (same as used in the hydraulic unit) for 24 hours prior to assembly. If they are not, they may not seal well when first installed.

3. If the gasket between the cylinder and the rear housing blows, oil leaks out of the cylinder and into the rear end. One symptom is that the oil level in the Powr-Trol keeps going down while the oil in the trans keeps going up. When replacing gaskets, be sure (on the A) to tighten to 150 ft. lbs. of torque.

It is also possible that even if these were done properly, there might be a defective seal or gasket somewhere. In addition, the cylinder itself may be defective (scored, cracked).

One way to check this is to raise the rockshaft and quickly back out the throttle valve screw (30-5-18 in SM-2011). If the TVS is backed out until it seats, in theory the rockshaft will not lower because oil cannot escape from the cylinder. If it still lowers with the TVS backed out, you probably have one of the above problems. If the rockshaft stops lowering, then you have a check valve or O-ring problem.

I have no magic ideas for testing the check valves. I've only had to take a few of these apart. Make sure everything is VERY clean, no scoring, reassemble according to the book (starting on 30-5-11) and I was all set.

The O-ring problems usually seem to be indicated by oil "drooling" around the plugs/oil line couplings.

First, look for a tag right next to the plugs with a "PCV" number on it. If you have an early style housing (PCV-100 through PCV-67904), each of the two plugs should use one O-ring (A3190R) and one V-Seal (AA3753R). (The V-Seal appears in the parts book to be made up of 5 small rings of some sort. Haven't ever seen one myself.)

If you have a late style housing (PCV-67905 or up) then each plug uses a total of three O-rings (total of six per valve housing), two small inner O-rings (A3190R), and one large outer ring (A3606R).

These details can be seen in the A parts catalog (PC675) on pages 127 and 128.

The only other suggestion I have is to go back to the list of items on page 70-5-1 in SM-2011 (troubleshooting section) and follow them again.

Good Luck!

(Additional information from B.A.) I have the early model with the V-seals. They are just 5 flat rubber washers that fit into the adapters. The way I understand, your (late style) plugs just insert into the box and the small lever on the side of the box locks them into place. My plugs insert into the adapters and then a C-clip is slid into place. Then a threaded collar goes over the end and screws down on the adapter.

The plugs in my style unit are made similar to but are longer than the ones you picture.

Also, I tried to find a tag on my unit where yours is and there is not one there. Instead, I was able to find one that runs horizontal instead of verticle, accross the bottom of the box. It only has the # 78 on it. No letters.

QUESTION: I was wondering if there is a way to have hydaulic hook ups and also have the rock-shaft turn for a 3 point? Or do I just need to plan on switching the plugs in and out when I want to use the hydraulics instead of the 3 point?

ANSWER: (the following information was provided by Mike) I use mine this way - looking from the back on the right side there are two square headed plugs. I screwed a elbow in each one, added a quickcoupler, and leave the powertrol plugs in. Now I can run the hitch and a cylinder with power up only (only in one direction). When I go to raise the cylinder, the hitch will come up first followed by the cylinder. When there is no cylinder attached, the hitch works normally.

There is one adjusting screw you can turn if you need the two-way cylinder to work properly, but it disables the hitch. The way I have described it works well most of the time. I just used one street elbow on one, and a short nipple and a standard elbow on the other (so they will clear each other) and screwed the coupler to the elbows.

Two-way set-upTodd's added note: I was at a tractor show and saw several Powr-trol units plumbed this way. I wondered if this indeed was the purpose of it. I have yet to sit down with the manuals and work out just exactly how the Powr-Trol unit does this, but I believe Mike when he says it works.

Note that Mike's set-up does not have the lengths of hose that the pictured tractor does, thereby eliminating the worry of catching the dangling hoses on something!

Also check this page for related information in a John Deere Service Bulletin!

If you have any other Powr-Trol information that should be added to this page, please let me know! That's the way we all help each other.