1989 Komatsu pc 150 swings slow/none

[Dannyboy63]

Greetings and Salutations from middle Tenessee!!! Heavy equipment virgin here (please be gentle!!!) So I bought a PC-150-3, an 89 model I believe. Long story short, swings slow in 1 direction and barely moves in the other. Motor lugs down (swear it smells like brakes burning) but no power. ALSO right track (moving forward) works fine with left track but will barely move independently....FIRE AWAY!!!

 

[Jgm]

How are your other functions? Does your pump make any unusual noises? Check your hydraulic filter for any foreign material.

 

[Dannyboy63]

The boom and bucket run great. The drive foward and reverse work great.

 

[Dannyboy63]

Also......checked the filter. No apparent debris and looks new...

 

[John C.]

First of all here is a video showing the maintenance for the machine. These are Dash 5s but most things are in the same place and done the same way.

All the problems you are describing are hydraulic or mechanical in nature. Do you have any gauges to plumb into the pump outputs? Travel issues can be caused by seals gone in the swivel, internal leaks in the travel motors or weak and unbalance pumps. The swing issues are concerning and sound a bit expensive to fix. Problems can be in the swing motor or swing machinery underneath. How much up and down play do you have in the house bearing?

 

[Dannyboy63]

Thanks for the video!!!! I went out today and poked around on it some today. I checked the play in the sluing ring by picking up the tracks with the boom on all 4 sides and it looked very tight, no noticeable play at all. The dash controls look to be hacked up pretty good. There was 4 wires, (3 red, 1 green and white, 1 purple) that came out of the cab and went between the boom and the cab and were cut. The track controls were mechanical, both joysticks mounted on valve bodies. Both the Swing and the Track issues get better when the its wide open... You can here the motor load up when you use the controls... If you can advise me on where to put gauges in the lines (and what pressures) I will gladly do so and I can start there!!

 

[Coaldust]

Don't the dash -3 machines have an electric swing brake switch under the left arm rest? Maybe it's as simple as the swing brake engaged. Or, maybe I'm mistaken. Paging JohnC.

 

[John C.]

There will be a square headed plug on the outlet blocks on each pump. The size is 1/8" BSP fitting but a 1/8" NPT fitting will go into the holes just fine. I put adapters in the have 1/4" JIC so I can hook up a hose and read the gauges from the cab. You need two gauges, one for each pump. I use a couple of 6,000 PSI gauges but 10,000 PSI would probably be better. You should also get a 1,000 PSI gauge.

There could be a problem in the swing brake system. If you look at the swing motor, you will see a small hose connected somewhere around the bottom or middle of the motor. The brake is spring applied and pressure released. It is operated by a solenoid. You can follow the hose back to a block that has some solenoid valves on it. Your machine releases the brake whenever any function is operated. It will stay released until you stop using things for about 7 seconds and then it will apply again. The function is computer controlled. If you look at your dash panel you should have a barrel switch that shows two or three positions. They will be S and L for a two position and H, S and L for a three position switch. Check which you have and let us know.

 

[Dannyboy63]

WOW!!!! The internet is AWESOME for this kind of stuff!!! It does have a swing brake switch that when "on" DOES prevent the cab from moving. I will get those fittings attached and get some gauges ordered. Please be patient as I will be out of town from the 7th-13th and am also building a 5.7 hemi for my magnum. I WILL GET THIS DONE!!! and then report back with my findings!!! Keep those cards and letters coming.......and THANK YOU!!!