maintenance
Accumulator Circuit
DANGER
Improper accumulator charging can result in an explosion causing serious injury or death! Never use oxygen or compressed air to charge the accumulator! Only qualified personal should perform
this procedure. Use only dry nitrogen to charge the accumulator. Contact your Mayco service department or your local Hydac representative for proper charging procedure
The accumulator circuit has two functions in the hydraulic system.
The accumulator circuit furnishes the hydraulic pressure to cycle the shuttle tube.
The accumulator circuit also furnishes the pilot pressure necessary to activate the hydraulic system.
The accumulator circuit is equipped with a bladder type accumulator (Figure 55) charged with 1100 PSI of dry nitrogen. The accumulator stores one gallon of hydraulic oil, which is, under 1750 PSI of pressure.
Figure 55. Accumulator
When the pump cycles, a part of the stored oil is released to the shuttle cylinder. This released oil pressure assures the shuttle tube has enough force to shear the cylinder of concrete passing from the concrete cylinder to the concrete delivery line during the cycle phase.
Checking Accumulator Bladder Pressure
The normal accumulator charge pressure should be approximately 1100 PSI. To check the accumulator pressure:
1.Start the engine and stroke the pump.The accumulator pressure gauge (Figure 30) should read 1750 PSI.
2.To determine the actual accumulator PSI, stop the engine and observe the pressure gauge. As the PSI reading slowly decreases, it will reach a point where there will be a sudden drop in the PSI.The PSI reading should be taken just prior to this sudden drop. If you do not read 1100 PSI, the accumulator may require charging or bladder replacement.
Wear Plate and Cutting Ring
Due to the abrasive nature of concrete, it is normal for the cutting ring to wear on its sides as it shears through the concrete inside the hopper.The
If the two components do not properly seat against each other, slurry will pump into the hopper rather than out the discharge line. See Figure 56. This condition can easily be observed.
1.The sudden change of the level of concrete inside the hopper during each pumping stroke
2.Concrete slurry squirting into the air from the hopper (Volcano effect)
3.When the output volume at the end of the delivery line decreases in pressure
4.Unusual frequent material packs in the Shuttle tube
It is important that the wear components be inspected weekly for proper sealing. Failure to inspect will eventually cause severe damage to the
If a deep groove or a wide space has developed on the sealing surfaces, it is time for replacement. Due to the motion of the shuttle tube, the cutting ring experiences a quicker rate of wear as opposed to the wear plate. The wear ring typically requires replacement two times per wear plate (2 to 1). When replacing the wear ring, also replace the rubber energizer ring.
page 48 — MAYCO LS600P CONCRETE PUMP • operation manual — rev. #0 (05/13/13)
