Home Forums General Discussion Technical Questions Dover composite leveling problem

I have a Dover composite that I make the master floor level in both directions, but have leveling problems at other floors. Is it posible for the pie plates to wear down enough to effect other floors? My brushes are good in both generator and motor and have also megged out both motor and generator.

Before you can set floor levels, you must first be sure the mg set is compounded properly, you should be able to the run car on inspection at level speed and get close to equal speeds up and. Usually around 10-13 fpm. To test the compounding first put car on inspect by removing the INA field wire from controller, then block out the MOX1 relay 3-7 n/ o contact to get level speed. Next make sure the 14 relay will pick up when you run the car by placing a jumper on FCP 3-7 n/ o relay contact which is on the left side of relay. Then run the car by either pulling in relay UA1, or DA1 by hand, or jumping S- to HAU or HAD in controller. The car should run at level speed in both directions, use a tach to measure speed of car, if the car runs in both directions within a few fpm then compounding is ok and you can then set the level switches. If the car will not run within a few fpm then you need to adjust compounding. For example if car runs up at 17 fpm and down at 8 fpm then you can not set floor levels with the level switches and cams properly. Many mechanics will start moving cams and level switches at the various floors to get the car to land level, this will only cause problems. The car must run at nearly equal level speeds before you can adjust floor levels. Once equal speeds are obtained then you can set up the master floor plate and switches for proper level. Once master floor is set you then need only adjust plates at other floors for proper levels. If you can not get equal speeds then you will have to adjust taps on generator, post back if u need help with this. First be sure brush riggings are clean,and all loop circuit wiring is tight, also spring tension on brushes should be good, no loose brushes in holders. Also all brushes must be seated properly, they should be smooth and shiny along the entire face of the brush. If they are not seated properly then you can not compound generator properly.

very good reply there Scott-great info! do you have the optical or micro switch leveling ring?

Thanks for the well explained description. Will check leveling speeds tomorrow. This particular unit has micro swithes for leveling but also have another unit with optical.

Ive changed out a couple of micros with the optos. The optos are more accurate and reliable than the micros. You can purchase the kits through Vertex. Its well worth it! But as stated by Scott you need to check your compounding for sure.

Great write up Scott! Good info.

man thats a great reply Scott. You can apply it to not only Dover but any MG installation really. Obviously the terminals and procedures might differ but the fundamentals are all there.

Thanks for the kind words guys, I must say that it is easier to talk about compounding a generator then it is to do it, as are most things in life. I love being able to walk into a machine room and compound a generator within a short time with no problems, but then there is always the generator that won't cooperate. What do you do then? Is the problem the generator, the motor or something else? Even after 25 years in the business, calling the boss to say pull the generator because it won't compound still leaves you with an empty feeling in your gut. What if your not right? Was the motor the problem? Was there something you overlooked? In my experiences, even if the motor is slightly grounded and the generator is slightly grounded pulling the generator first usually does the trick. We have had quite a few generators that go to the rewind shop for cleaning and still won't respond when installed. Usually the motor shop will say nothing is wrong with the generator and you must prove them wrong. When this occurs I will run another car with the suspected generator to prove who is right. Once proof is obtained the generator is usually fully rewound to cure the problem. Lucky for you young guys that mg sets are fading away with the installation of ac motors. No more nasty carbon to breathe and bring home for your wife to wash . Ahhhh to be young again

Thanks for info I’ve Tryed all of the above had motor shop there twice they say it can’t do what I’m saying. All I do is sometimes pop brushes & sometimes have to reseat. Runs perfect for about 3 days. Been doing this for 40 yrs & never saw nothing like this. Thanks for input tho!

bear in mind that the 1/8" cable stretches all along the length of the cable, not all at one point. This makes the floors off slightly above and below the master. This will alter slowdown distances above and below the other floors. Final leveling may compensate for some of this, but if you are driving into the floors, early or late slowdowns will take a toll. Have you replaced the cable recently?

What kind of brushes are you using. We used to have brushes made where Otis had theirs made and they made some changes and we had all kinds of problems. For one, pull the leads on the brushes to be sure they are attached inside properly. Is composition correct (Brush Grade)? Grade on Motor and Generator? Does Armatures have a glaze on Motor and Generator. If so and the grade has changed, the glaze may not be compatible. Motor Grade and Generator Grade are usually different as you probably know and are not interchangeable. Trying a different brand in both could help. Your problems sound like problems with brushes. The strength of interpoles in Generator affects compounding strength tremendously. On many Otis 71 & 82 Generators when I was at Otis, we changed the interpole shims from brass to steel to change the strength and create stability. The strength of interpoles is determined by doing a "Black Band Test" which is quite involved.

When the Dover Composite was put into service, the Brush was a National SA-45, they ran great with no issues. Then Dover changed to what they called the super brush. I can't remember who the manufacturer was, but they worked well also. When ever you change from either of those 2 brushes, you will invariably have compounding issues. That said, the advice about the the stretch of the selector cable is very true. One other thing I have encountered is the brake drop relay hanging in with residual, and the R C circuit that is in the brake drop, can also give you a compounding look. Last but not least the brake core itself may need a good cleaning. A quick check to see if it is the brake, is to put some pressure on the brake shoes, holding them together with your hands. If the car stops level you need to look at the above.

Excellent post Scott. One little trick I like to use which saves you a trip if you dont have your tach which btw is hard to run the car and hold a tach on inspection. Put two marks on the drive sheave about example 12:00 and 3:00. Using the stopwatch on your phone, while running the car via UA or DA relay, time the sheave to go from mark to mark each direction. It will be very easy to determine which direction is faster. One of the other mistakes guys don't realize is often you will only get about 1/2 a brush use. You are working with brush holders that have long lost their effective tension.