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  Open Loop (standard) /
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Conveyor Braking Packages are unique in some way for each project.  The elements involved are common (calipers, disc, hydraulic unit, etc...).  The most significant functional difference is in the controls.

Standard units use an open loop system.  Stopping time is approximated.  The actual stopping time depends on the conveyor's belt load.  Braking time is affected by changing an adjustable orifice within the hydraulic unit.

Smart units are a close loop system.  The brake system's PLC is programmed with a PID loop that establishes the rate of deceleration (slope) and regulates a proportional control valve.  Stopping time is consistent regardless of the conveyor's belt load.  A more detailed description can be found on subsequent pages.

PT Tech used wither SIME or Delmar calipers and Allen Bradley PLC's.  However, PT Tech has supplied totally enclosed wet brakes for conveyor system.  The largest one to date has a torque rating of 80,000 lb-ft.  Wet brakes are special and designed per project.

Please contact PT Tech for more details.
 
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SPECIFICATIONS
  • Allen-Bradley SLC 5/02
  • Programmable stopping time
  • Panel mounted status lights
  • 230/460 VAC
  • UPS (15 minute)
  • Door mounted electrical disconnect
  • Internal 110 VAC outlet
  • Tachometer
  • 24 VDC operating system
  • NEMA 4 enclosure
  • Wall mounted
  • Weight
  • 24" x 36" 12"
 
SPECIFICATIONS
  • 230/460 VAC
  • 5 HP Motor
  • Mineral Oil grade L-HM or L-HV type HM32 or HV32
  • Operating pressure: 2540 psi min. 2900 psi max.
  • Maximum working pressure.  3045 psi (210 bars)
  • NEMA 4 wall
  • Locking valve with limit switch for hand pump circuit
  • Pressure Gauge with shut off valve
  • Proportional valve sized to control pressure from accumulator and brake
  • 24 VDC solenoid valves
  • High pressure filter switch from reservoir
 
PT Tech's closed loop braking system (Brains & Brawn)
couples a PLC, tachometer and proportional control valve "Brains" to an open loop system "Brawn".  The adjustable orifice in the open loop system acts a redundant circuit for the proportional control valve in the closed loop system.  Conveyor stopping time is independent of the load.

Brains
PT Tech's "Brains" include an Allen Bradley SLC 5/02 PLC with PID loop capability, DC tach generator and a proportional control valve.

Electronics

  • Allen-Bradley SLC series is a proven product that is familiar to the mining industry.
  • PID loop allows for a consistent stopping time regards of the load on the conveyor.
  • PLC can be upgraded to allow for sophisticated communications between the communications between the conveyor's PLC and the braking system's PLC providing real time information.
  • PLC controlled proportional valve is assed to the standard hydraulic package.
  • The system's UPS allows the PLC to operate during power outages.
 
PT Tech's open loop braking system (Brawn)
uses spring applied direct acting caliper disk brakes and a hydraulic power unit.  Brakes are applied when system pressure drops across an adjustable orifice (tamper resistance).  Conveyor stopping time is dependent on the load.

Brawn
PT Tech's hydraulic power units are made from off-the-shelf components.

The brake and hydraulic unit can be equipped with transducers/sensors/switches that provide important system status data.  A large accumulator allows for smooth braking over stopping times up to 30 seconds.

Hydraulics

  • All components are readily available from local sources
  • Hydraulics and electrical circuits are housed in separate enclosures
  • Quick disconnect fitting located on side of pane to brake.

Brakes

  • Direct acting calipers are very reliable and low maintenance
  • Pivoting shoes allow for even wear on friction pad
  • Independent stroke setting for each caliper half makes on site adjusting easy.
  • Three brake caliper sizes and customized disc diameters are available.
 
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TELEPHONE: 330.239.4933  |  FAX 330.239.2012
1441 WOLF CREEK TRAIL  |  P.O. BOX 305  |  SHARON CENTER, OH USA  44274-0305
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