Setting Telebelt Feeder Lift Pressure Switches

Function:  When the main conveyors are slewed, the brakes on both the feeder and the main release.  If this happens with the feeder off the ground, the feeder will:
a) swing behind the main conveyor like a real long counterweight, or
b) take off downhill if the machine is not level.

The feeders are raised hydraulically, but they lower by gravity as the oil passes through an orifice.  The feeders must be fully lowered for the mains to slew.  It looks like you are “powering down,” but you’re just letting the cylinder and rails relax.

If there is enough pressure in the feeder elevate circuit, the (NC) pressure switches open and break the connection to the slewing valve.  The WBV valve still goes to the “boom” side.  One switch disables slew right and the other disables left, and they are both connected to the feeder lift line through a manifold block.  No oil flows to release the brakes when the slewing valve doesn’t throw.

Symptoms:  Main will not slew left, but slew right works, or vice-versa.  It’s very rare for the main to not slew in either direction because of pressure switch adjustment, but it can happen if there is enough pressure on the system.  All functions work manually.  Cable remote makes no difference.

 “Field Fix” (to complete a pour):

  1. Make sure the feeder is down fully.  All pressure must be off the feeder elevate cylinder.
  2. After confirming feeder is firmly on the ground, try manual control.  Make sure to move the WBV (selector valve) andthe slewing valve.  If it still doesn’t slew, the problem is not the pressure switch.  If the main does slew, options are:
    1. Operate slewing manually to finish the pour.  Keep the feeder firmly on the ground while slewing the main.
    2. Bypass the pressure switches by:
      1. Removing the plug connector from the top of one the switches.  On a 110, it might be necessary to remove the fan shroud to do this.  If the problem is unchanged, that is the correct plug.  If it now won’t swing either way, replace that plug and remove the other one.
      2. Put a jumper wire between pin 1 and pin 2 of the plug.  A piece of tie wire will do.  Do not reconnect the plug, but tie it out of the way to keep it from shorting.
    3. Alternate bypass – Jump X10-17 to X10-18 for right or X10-19 to X10-20 for left.
    4. This is a temporary fix and permanent repairs MUST be made before taking the unit out again. 

     

    Procedure for Setting Telebelt Feeder Lift Pressure Switches

    NOTE: THIS PROCEDURE CAN ONLY BE PERFORMED WHEN THE SWITCH IS INSTALLED IN THE CIRCUIT. THESE ILLUSTRATIONS ARE MERELY FOR SHOWING THE SWITCH.

    The feeder lift pressure switches are installed to prevent the main boom from slewing when the feeder is off the ground.  This is a safety system.  The switches are installed in the feeder elevate hydraulic circuit.

    To set the switches, you need a continuity tester, 1/8” Allen wrench and a flat-head screwdriver.

    Procedure:

      1. Support machine with outriggers.
      2. Unstow the feeder from the rest on top of the main boom and slew feeder to side of machine.
      3. Lower empty feeder (NO HOPPER OR ATTACHEMENTS) until the feeder legs are 1 to 2 feet off the ground.
      4. Turn off the remote.  The truck engine can also be shut off.
      5. Remove wire connection plugs from both switches.
      6. Remove small brass screw adapters from both switches.  These are the adapters that the plugs screw in to. 

      1. Connect a continuity tester to terminal #1 and #2 (terminals are labeled on switch and plug)

      1. With 1/8” Allen wrench, turn the pressure adjustment screw in, (screws are located under the brass screw plug you removed), until you get continuity, then back screw out until you loose continuity.  From this point, back the adjustment screw out ½ turn more, this is your final setting.

    1. Repeat steps 8 on the other switch.
    2. Reinstall the brass screw adapters and wire connection plugs.
    3. Restart the engine, reset the remote and test the settings by lowering the feeder to the ground, then lift main boom out of the boom rest and slew main boom to the right and the left.  The main boom should slew.  Then raise the feeder off the ground and slew main boom right and left.  The main boom should not move.

Telebelt Receiver Fuses

The e-stop circuit of Telebelts includes the HBC 735 radio receiver.  Actually, the e-stop circuit supplies power to the radio receiver. 

The images below, A370160 Pg 4 and Pg 5 show the circuit. To view at a larger size, click on each photo individually and they will open in a new window.

The 12V supply (red) goes through the e-stop stations to X81 pin 13.  X-81 is located on the right-hand (hinge side) of the control cabinet.  The power then goes through a fuse in the radio receiver and returns to X81 pin 5, and then through the e-stop stations to 4A17, the e-stop relay. 

 

 

 

This image shows the pin locations on X81.

 

 

 

 

 

 

The image shows the inside of the 735 radio receiver.  There are 4 fuses called out in the image, and their reference numbers correspond to the reference numbers in the image that follows.

 

They are:

42 = Power supply primary – 6.3A

43 = Power supply secondary – 1.0A

44 = Proportional output card – 12.5A

45 = E-Stop card – 4A

 

 

All of these fuses remove by pushing the end cap in slightly and rotating it to the left.  When the cap releases, a spring pushes it out a little.  The fuse will be attached to the cap.  You might need a coin or flat blade screwdriver to remove the cap.

 

RULE #1 – The problem is NOT in the radio system

 

Symptoms of a problem:  

 

E-stop will not reset and there are no LED’s lit on the receiver.

 

FUSE FAILURES IN THE RECEIVER ARE RARE.  Make sure you check all the way through the e-stop circuit (SEE RULE #1).  A blown 4F17 or a bad e-stop button causes the same symptoms.

 

If you have no power at pin X81-13, the problem is NOT in the receiver.  If you have 12V at X81-13 and zero volts at X81-5, check fuses 42 and 43 in the receiver.  Either one of these fuses, when blown, cause these symptoms.

 

Before replacing any fuses and turning power back on, find the short.  Likely places are faulty e-stop buttons or their boxes, or cable shorts between X81 and the radio receiver.  The 90’ cable can be substituted for troubleshooting purposes.

 

E-stop will not reset and there are LED’s lit on the receiver.

 

SEE RULE #1.  There are many possibilities, including:

  • Remote switch problem.  Verify with cable remote
  • See control box schematic:
    • Blown 3F64
    • 4K69 or 3K275 bad or unseated – confirm by flashing 4A17-T33 to 4A17-T-34
    • 4A17 connections bad
    • 4A17 defective
  • Problem with receiver cable from X81 – use 90’ cable to confirm

 

If all else doesn’t correct the problem, check 4A fuse #45 on the e-stop card.  If the receiver cover is off, you will see the “light show,” but attempts to reset will just cause relays on the card to click.

 

E-stop will reset and there are LED’s lit on the receiver.  Only non-proportional functions (toggle switches) work, but moving joysticks only cause the WBV (Boom/Outrigger) selector valve to move.  The actual function levers do not move.

 

RULE #1 might not apply.  This is opposite from when the pilot valve relay is bad, or when you turn on the transmitter but don’t reset.  In that case, the function levers move but the WBV valve does not.   Just to be sure, use the cable remote to confirm the radio problem, then check the 12.5A fuse #44 on the proportional output card.

 

Before replacing any fuses and turning power back on, find the short.  Likely places are faulty cables or plug connectors on MBC valve, or cable shorts between X81 and the radio receiver.  The 90’ cable can be substituted for troubleshooting purposes.

BOOM PUMP: Proximity Switches

Your Putzmeister boom pump uses proximity switches (aka prox switch) to cycle the pump. Some quick tips to keep them from being a misunderstood part on your pump.

 

What might go wrong?

Prox switches are screwed directly in to the drive cylinders and are subject to high pressure hydraulic oil. It is common to over tighten them, they take 14 foot pounds of torque which is a relatively low torque. Because they are in the pump hydraulic cylinder subject to high pressure oil they are quite often over torqued, this distorts the switch and it will fail early or not work correctly. The prox switches have a high pressure seal to handle the pressure subjected to them.

Next prox switches are grounded through the cable not the cylinder, so to test the system you can take a new switch, plug it in, touch it to metal and it will trigger. The switch works from magnetic principle, the piston is steel and the switch is triggered by this steel piston passing under it.

PMA Prox Switch Testing

PMA Prox Switch Testing

Deciphering the Light and Wires

On top of the plug you will see two LEDs one is green and one is yellow, The green one indicates that power is getting to the switch, the yellow one is the trigger signal that indicates the piston is under the switch sending a signal to the relay.

The prox switch wires go back to the distribution box, this box combines the signal to send it to the stroke change relay, LEDs are located at this box to tell you if they are working, you might have four or six switches on the standard units.

We encourage you to watch the lights when you are cycling the unit to clean the water box. You should see the yellow LEDs flash when the piston is passing under the switch; you have two switches at each position. They are working together as a backup which means if one fails you are still pumping.

PMA Prox Switch LED Lights

PMA Prox Switch LED Lights

Ways Prox Switches Fail

Switches can generally fail two ways, the yellow LED does not turn on when the piston passes under it, this is the most common failure. They can also fail by being stuck on. The yellow LED will be on even though the piston is not under the switch. In the first case no action is necessary, but if the switch is stuck on it will need to be disconnected from the system as it will interfere with the cycling of the relay. Simply unplug the one that is failed on, and resume pumping.

We all know that if it can go wrong it most likely will, this is the reason for the redundant-style system. However, quite often due to lack of maintenance or lack of understanding one switch will fail, then at some point the other switch will fail and now you have a problem. So familiarize yourself with the system and check it frequently so you can avoid being down due to prox switch failure.

PMAProxSwitch2

The pictures show a model used in the Putzmeister Service School class room to demonstrate the switches and the cylinder position, as well as, testing a switch not installed on a unit.

BOOM PUMP: Having E-Stop Issues? Simple Things to Check.

This relates to standard 12V units as well as early European 24V units.

Every component in your Control (aka Combi) Box should be labeled; age and changing parts without putting a sticker on the new part can lead to problems. In the image the decal shows 10A17, yours might say 6A17.

E-stop

Deciphering the Number

The first number, 10 or 6, is the page number of the schematic that you will find this component on. All components in the Combi box work this way; for example, 6F76 is the fuse for e-stop on page 6. The page number of the schematic varies with the options a unit has, or the amount of revisions to a particular unit. We can go into revisions later.

The letter, A, is the code for the part, A= Assembly, F=Fuse, S=switch, K=relay. Notice a German unit’s code letters are the same as English.

The second number, 17, is the assigned number for the device. Notice 10A17 and 6A17 are the same part just different pages in the schematic.

So You Are Having Issues With The E-Stop? A Quick Test Will Reveal Why.

Look at top left and find Terminal A1 (+), also in the lower right find A2 (-), putting a voltage tester at these 2 points will tell you if you have voltage. We NEED to use a voltage tester not a test light to see how much voltage we have here. Note: The red locking paint might need to be cleaned a little at the screw to get a good test.

For this relay to reset and hold you need to maintain 12 VDC, these 2 pins are powering a coil that is rated for 12 VDC. If you hit an E-stop button on the unit or turn off the remote, the voltage disappears and the relay unlocks, the 2 green lights go out and nothing works. So if you have no voltage here check the E-Stop buttons on your remote and if the local/remote switch is in the center position. A quick test for checking the remote is to set the local/remote switch to local and check for voltage. If the E-Stop resets and you have 12(+- 2 VDC), you have a remote issue, try your hard wire remote.

As previously, mentioned, always test with a voltage tester not a light, also test using the A2 (-) pin for ground, this is the ground the relay is using, If the wire from A2 to ground is bad the relay won’t set either. A quick check for this is: positive lead on A1, negative lead on A2 and look at the result, then move the negative lead to main ground in the Combi Box and look at the result. No or low voltage at A1 and A2, and 13.6 at A1 and the main ground point tells you that your problem is a bad ground from A2 to the main ground, follow that part of the circuit.

Voltage Drop

Most of the time the issue is voltage drop. I get a comment like “I get the E-stop to clear and start pumping then I hit 2 or 3 boom functions and it goes back into E-stop. If I do one function at a time it stays on.”  To avoid this or find the issue you need to test for voltage drop at A1. You can do this with the boom closed just don’t put the transmission in gear; have someone assist you with the remote, make sure the engine is running, PTO ON, not in gear on the transmission, this way you can activate the electrical components and not bend boom arms. That’s a different Tricks of the Trade post.

Check for the voltage at A1 then clear the E-stop by honking the horn, turn on the pump and see the voltage drop a little, next hit A arm, it dropped a little more didn’t it,“ then B, then slewing, then tip. Each function you activate is more draw on the circuit and at some point the E-stop relay will drop out. Not from a bad E-stop button but from voltage drop.

The problem is current flow. Look for loose or corroded wires in the E-stop switches or in the cable powering the remote receiver. Open the boxes and look at the wires, are they loose? Give them a little yank did it pull out of the terminal or sleeve? One common source for resistance issues is corrosion in the cable due to washing the pump with acid. Acid loves concrete, copper and chrome, it is not recommended to use acid to wash pumps. I have seen it turn the wires green as far as 3 feet inside the plastic coating, a major source for voltage drop. Poor grounds for the Combi Box and poor power from the truck are also big issues as the unit ages.

Take the time to do this easy test, if your voltage drops you can dig a little deeper to locate the problem and avoid future issues by resolving the problem now.

Do  Not Bypass E-Stop.

This is also the time to mention that bypassing the E-Stop is a serious problem, if the power is not at the A1 pin then even if bypassed the remote won’t work. This is due to the fact that the remote is being powered with this same circuit. So bypassing is not the best way out of problems it presents major safety issues and most likely won’t get you up and running on the remote.

As mentioned in the beginning, this is the basic start to troubleshooting the 12V Combi Box. If you have a 24 V ZMSK box the E-stop circuit is a little different, contact the Service Dept (800-890-0269), e-mail me (woodsa@putzam.com) or comment on this post and we can go deeper into the particulars.