Monthly Archives: June 2012

Belt(s) won’t run? I’ll bet it’s not the pump.

Belt(s) won’t run?  I’ll bet it’s not the pump.

 1 of 3 – Mechanical

This is the first of three articles about Telebelt belt-related problems.

From time to time, I get calls involving a belt that won’t run, or runs very slowly.  The call I like the least is, “My feeder (or main) belt quit running.  I replaced the pump, but it still won’t run.”

With over 800 Telebelts in the field, we are looking at more than 2,100 piston pumps.  We don’t hear of pump failures very often.  Even if we go back to the Super Swinger 105s, of the early 90s, many are still running original pumps.

So, again, I’ll bet it’s not the pump.

Rule # 1 – Check to see if it will run with manual control.  If it will, the problem is probably electrical or in the radio.  If not, it’s mechanical or hydraulic.

Things that stop belts: 

  • Mechanical problems
  • Electrical problems
  • Hydraulic problems
  • Truck or engine failure.  This is beyond the scope of this series.

Let’s deal with mechanical problems, since they are the easiest to spot.

Are the PTO shafts turning? 

  • Actually look at them.  I once spent an hour on the phone with an operator who has just moved and set back up and his belts wouldn’t work.  I finally got him to look under the rig, where he found a pump drive shaft lying on the ground.
  • Is the PTO engaged?  Snow and ice can jam a PTO linkage.  Pins can fall out.  Air lines can leak.  PTO shaft gears can strip.

Do the hoses jerk, like there is pressure?  Does the belt move a little?  Put a pressure gauge on the test port.  If there is 280 bar, and nothing is moving, look for:

  • A seized 5” pulley
  • A seized feeder drive pulley
  • Over-tensioned scraper – Yes, that can stall a belt.  It can also stall a belt that is heavily loaded.
  • Rocks packed at tail pulley (feeder) or drive pulley (main).
  • Rocks packed at the heel of the arm back from the tip section (arm 3 on a TB-105 or 110, arm 4 on a TB-130).  There is supposed to be a v-scraper there to guard the close clearance between the heel pulley and the steel end frame.
  • Feeder motor hoses kinked.  Active (hydraulic lift) feeder machines (TB130, 80 & 110) can do this if the feeder is slewed more than one time around.  On 105’s, feeder lines can get pinched in the transfer.  Also check 105 feeder line quick connects to make sure they have not backed out.
  • Is more torque required?  This is as much a hydraulic issue as mechanical.  Most Telebelt feeders operate just fine with 130cc motors.  Belts that are heavily loaded, paving for example, might require 160cc motor.

Do you think oil is flowing but there is not much pressure? 

  • Feeder – check for stripped drive pulley collet or broken motor shaft.
  • The Main has 2 motors that plug into splined adapters welded into the ends of the pulley shaft.  If the welds on an adaptor break, that motor will be free to spin.  You will hear oil going through the motor.  Operators have finished pours by capping the lines to the “bad” side motor, thus forcing the other motor to drive the pulley.
  • Check main motors for broken shafts.

Are the belts tight enough? 

  • Feeder belt pulleys are more likely to slip, especially if they are the old-style steel-lagged pulleys.  Maintain feeder tension at 1,500 to 1,800 PSI.
  • Once in a while, you will find a ready-mix driver that will wash what he spills.  If he gets the back side of a loose feeder belt wet, the drive pulley might slip. 
  • Main conveyor pulleys are less likely to slip, even if the belts are real loose.  Worn or missing drive pulley rubber lagging leaves a steel surface that will slip.  Maintain main belt tension at 1,000 to 1,200 PSI.
  • Keep lagging grooves, on main and feeder drives, free of grout buildup.

 

 

Test Lights and Bad Grounds

Test Lights and Bad Grounds

Test Light – A probe-type device that lights up, under certain circumstances.  Sold in automotive and other novelty stores, it is used to troubleshoot simple electrical circuits, and other witchcraft.

Test lights are great for troubleshooting tail light circuits on your boat trailer.  They have NO business inside a combi-box.  Telebelt combi-boxes have circuits carrying 24v, 12v, 5v, variable voltage and signal circuits that are read in milliamps.  You can complete circuits, and cause components to fry.  In other words, you can “let the smoke out.”

Basic Rule of Electricity #1 – Smoke makes all electrical things work.  Smoke makes computer chips work. Every time you let the smoke out of a computer chip, it stops working.  Electric motors have to be large to handle all that smoke. A lot of smoke leaks out when they quit working.

Use a multi-meter.  Get one that measures DC voltage, amperage and resistance.  You don’t have to spend hundreds of dollars for a top-of-the-line Fluke meter.  You can get one for less than $10, and it will do what you need.  Keep it in your combi-box.  It will live longer there.

Sooner or later, you might end up calling in with an electrical problem.  You should have a copy of your schematic and a meter.  You are our “eyes and hands” when we troubleshoot over the phone.  We’re not much help if you can’t furnish voltage readings for us.

Bad Grounds

Some of the most difficult calls we get are traced to bad grounds.

I recently had a call from an owner that could not get his TB-105 e-stop to reset.  After going through the steps to figure it out, I determined his e-stop relay was toast.  This was an older TB-105 with a negative Mack battery disconnect.  These were notorious for high resistance at the wire contacts of the Mack switch.  Electrical components that are not properly grounded, can fail.  E-stop relays were particularly sensitive.

I wanted him to check his ground, but he didn’t have a meter.  He did have a test light that lit when he touched the positive and negative terminals of the e-stop relay.  That really doesn’t tell me all I need to know. 

He went and got a $5 meter.  When he connected the meter to the positive and negative e-stop terminals, he read 13.8 volts, since the truck was running.  Then I had him connect the negative lead of the meter to a frame ground and touch the positive lead to the ground side of the e-stop relay.  He read 2.3 volts.  I had him touch the positive lead to the M12 screws (combi-box ground) and he still read 2.3 volts.  In both cases, he should have read zero.

The problem will be traced to the connections on the Mack disconnect switch.  NOTE:  When loosening or tightening nuts on the back side of the switch, use 2 wrenches.  There is a wrench flat at the base of the studs.  Use one wrench on those flats to keep the studs from turning and twisting the wires off internally.

Another way to check the ground is by resistance.  Set your meter to OHMS.  Checking between M12 and a frame ground should read nearly zero ohms.  There is resistance in the wire.  Some meters have a continuity tester in the ohms scale.  They should “beep” when checking this way.

Oh, and meters can check diodes, too.  This way we can help you find the smoked diode in the 25 AMP fan circuit that somebody put a 40 AMP fuse in.