Monthly Archives: March 2013

Update on Telebelt Belt Circuit Adjustments

SETTING PRESSURES ON TELEBELT BELT CIRCUITS.

The main conveyors and feed conveyors of Telebelts are two separate hydraulic circuits.  Each has their own pumps, control valves and motors and they are hydraulically independent of each other.

The hydraulic pump capacities vary.  Different models have different pump sizes, depending on belt length.  In addition, Telebelts that have direct drive pumps (TBS) and automatic transmissions use pumps that have capacities that differ from manual transmission Mack counterparts.

This is about pressure setting, not capacity.  Capacity (flow) determines belt speed.  Pressure is the resistance to flow.  If the pressures are correct, the pumps should deliver the required flow.  Pressures are checked with pressure gauges, supplied with the machines when new.  Flow is measured with a flow meter, which is not supplied.

Again, flow determines speed.  A “working man’s” flow meter is a stopwatch.  Data sheets, provided with the machines show function speeds when the unit was in final test.  For example, a test sheet might show 65 seconds to slew the main boom 360 degrees to the right.  If you obtain the same results, with pressures properly set, you can be sure the circuit is still operating as new.

Some things that can affect speed are; low throttle setting, pump wear, motor wear and filter conditions.  You have the tools to check the pressures, so here we go.

Take all test readings from port M1A, for the main conveyor, and M2A for the feeder.  Ports M1B and M2B are load sense ports used by the factory.

There are two pressure settings for each pump.  They are the Low Pressure, a.k.a. “stand-by,” and high pressure.

 The illustration is a TB-110.  The TB-80 is controls mount the same way, but the TB-130 and TB-600 have the controls “laid down” so the volume control knobs face you.  As a result, the TB-130 and TB-600  M1A and M2A  ports face downward.

You will need the 60 bar and 400 gauges, supplied with the Telebelt, to check the pressure settings.  ALWAYS connect the 400 bar gauge first, since there could be more than 60 bar in the circuit of a belt that is not moving, depending how the belt cards are set.

Gauges can be connected when there is pressure on the circuit.  It is not necessary to disengage the PTO’s to connect the gauges.

Pressure adjustments can be made at idle, or just above.  It is not necessary to go to full RPM.

Compensator adjusting screws will have either a lock nut and Allen screw, or an acorn nut that, when removed, exposes a lock nut and Allen screw.  Release the lock nuts and turn the screws IN (clockwise) to increase pressure, or OUT (counter-clockwise) to decrease pressure.

On Mack Telebelts, the front pump on the driver’s side is the main belt pump.  The pump attached to it is the feeder belt pump.  On Telebelts with a transfer case (TOR, Sterling) as well as TBS units, the first pump is the main belt and the second is the feeder.

Setting low pressure, main belt:

  • Start the Telebelt and engage the PTO’s.

    Method 1: DO NOTreset the e-stop.  If the motor control valves are energized, false readings are possible if the belt card zero screws are set too high.  Open the load sense shut-off valve manual bypass.Alternate method:  Reset the e-stop, but disconnect the motor control valve connectors, pull the belt cards out, or remove the belt card fuses.  This will turn the load sense valves on, electrically.  Opening the bypass is not necessary.

    Either method will produce the same results; 1. Load sense shut-off open and 2. no power to belt control valves.

  • Connect 400 bar gauge to M1A and make sure pressure is below 60 bar.
  • Switch to the 60 bar gauge on M1A and read the pressure.  Compare this to the original reading on the test sheet in the front of the manual.  It will probably call for 20 bar.  If the correct pressure is not read, adjust the low pressure setting screw.
  • Remove the 60 bar gauge.

Setting high pressure, main belt:

In order to check high pressure, you have to cause the function to go to relief.  In other words, you have to stall the belt motors or block the flow to the motors.  You can cap the hoses to both motors, or reverse the lines to one of the motors, which cause them to turn against each other.  I prefer the latter.

  • Let the air pressure off the hydraulic tank (TB-105 and TB-110 only)
  • Reverse the hoses to one of the main belt motors.
  • Re-pressurize the hydraulic tank (TB-105 and TB-110 only)
  • Connect 400 bar gauge to M1A
  • Start the Telebelt and engage the PTO’s
  • Reset the e-stop
  • Turn the main conveyor on.
  • Gauge reading should be 280 bar.  Adjust as necessary.
  • Shut Telebelt off and de-pressurize the hydraulic tank (TB-105 and TB-110 only)
  • Return motor hoses to their original position
  • Re-pressurize the hydraulic tank (TB-105 and TB-110 only)
  • Remove 400 bar gauge

Setting low pressure, feeder belt:

 Use the same procedure as for the main, except test at M2A.

Setting high pressure, feeder belt:

Use the same procedure as for the main, except test at M2A.  To block flow in the circuit, cap the pressure line going into the feeder motor.  This is the line that DOES NOT have a “T” in line.

Current production pressure settings – November 2010

 Standby Pressure

Main conveyor pumps except TB(S)-130/600 = 20 bar,  TB(S)-130/600 = 25 bar

All feeder belt pumps = 20 bar

All boom/outrigger pumps = 22 bar

High Pressure

ALL PUMPS = 280 bar.