1.HOLDING vs. Control brakes 2.Regenerative Braking. HOIST BRAKES Load Brakes vs. Motor Brakes vs. Dynamic Brakes, vs Magnetorque Brakes 5/10/2013

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Rafe Richards
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1 ANSWERS to TECHNICAL QUESTIONS Every thing you ever wanted to know about HOIST BRAKES NOT JUST LIFTING THINGS, BUT ENTIRE BUSINESSES Mike D. James Vice President & GM Industrial Cranes General concepts across Many Product Lines 1. HOIST BRAKES Torque Requirement 2. 2 nd BRAKE SYSTEMS 3. DC vs. AC 4. Regenerative Brakes 5. Mechanical Load brakes 6. SHOE Brakes vs. DISC Brakes 7. Disc Brakes vs. DISC Brakes 8. IS there a BEST Brake? 9. What should YOU specify? ALSO SEE HANDOUT COMMON Brake TERMONOLOGY COMMON Brake TERMONOLOGY Brake Shoes, Linings Brake Discs Dynamic Braking Modules Braking Resistors Brake Alternator Off position Braking Traverse Brake = Bridge, Trolley Hoist Brakes Motor Mounted Brake Brake Wheels Lock Nut Slotted Unslotted Tapper Bore Supernut Material types: Cast Iron, Steel, Carburized Brake Pot Brake Coil Brake Armature Link, Arm, Rod etc Brake Rectifier Impulse Actuator Thruster Hydraulic Brake Master Cylinder Brake Cylinder SBESBMSBISB GPGPEGPIGPM CD SD DISC BRAKES HOIST BRAKES Load Brakes vs. Motor Brakes vs. Dynamic Brakes, vs Magnetorque Brakes Magnetorque = Eddy Current While I will attempt to touch on most of these items I will focus on just 2: WHY DC? Vs AC? brakes SHOE Brakes (larger motors) Thruster type actuator vs. Magnet actuator What is an EDDY Current? WESTON TYPE Mechanical LOAD Brake 1.HOLDING vs. Control brakes 2.Regenerative Braking Your handout will fill in many of the blanks. 1

2 Overhead Crane Safety Considerations Meeting Current Standards ASME B30.2 American National Standard for Overhead and Gantry Cranes. Rev w/1998 Addenda OSHA (Code of Federal Regulations) Article 29, Part , Rev. 7/1/97 CMAA Specs #70 and #74, Revised 1999 AIST Spec 6, NEMA Brakes: DISC Type HOLDING BRAKE Hoists shall have a holding brake and a control braking means. ASME B30.2 Equipment Safety Requirements FEM, ISO and others. Shoe type holding brake with DC MAGNET actuator coil Eddy current control brake HOLDING BRAKES STOP & Holds Motor Brake Shoe Brake Electric Disc Brake Mechanical Load Brake Locking Worm Gear Load Brake COMMON Brake TERMONOLOGY Control Braking Means Slows / Controls speed Mechanical Load Brake Weston type Locking Worm Gear Magnetorque Eddy Current Dynamic Braking Regenerative Countertorque Fail Safe = Spring set & Requires Electrical Power to release SOME BASIC ELECTRICAL FACTS There are AC Brakes And DC Brakes WHICH are Better? DC = ONE WAY power ALL AC coils use LAMINATED cores Circulating Eddy currents GENERATE HEAT Laminations help break up & Isolate Eddy currents & Heat DC vs. AC and eddy currents 60 HZ DC vs AC DISC Brake Advantages. FACTS: ALL AC COILS GET HOT due to EDDY CURRENTS AC coils use Laminated steel poles to break up and minimize EDDY Currents. Laminations fail / vibrate Buzzz cause coil failure HOT coil adds to Brake lining heat AC reacts releases very fast = Hammering action SHORTER coil life Lining life PLUS all DC brakes are NOT EQUAL DC coil = NO EDDY currents DC coil = COOL no extra heat DC coil = SOLID no lamination construction DC coil = SLOW release miliseconds to create DC Slower flux buildup BETTER POSITIONING 2

3 TYPICAL DC DIRECT ACTING Hoist Brake P&H D.C. Rectified Disc Brake Sizes Models DC Rectified for cooler operation & positive positioning 150% Braking Torque Min to as much as (170220%) SOME MANUFACTURERS offer : Minimal if any Brake adjustments for life of the lining and 1 Million operations SD1.410 ft lbs CD1 CD2 CDH CD3 CDD CD4 CD5 CD Ft lbs 2 nd DC ELECTRIC HOLDING BRAKE is usually an AVAILABLE OPTION TORQUE LIMITS Typical SHOE Brakes SelfAdjusting SHOE Brakes Most brakes must be continually adjusted as the lining wears-and this involves troublesome mechanical linkages, starwheels, or like devices. Plus costly downtime. SHOE BRAKE Sizes Uniform Torque Ratings Uniform Shaft / Wheel Height Uniform Mounting Bolt Dimensions GP AISE GP Brakes GPE GPI GPM GPA GPML GPMW NONNEMA sizes Lower cost Lighter duty 3

4 AISE/NEMA Rated Impulse Brakes Impulse Actuator or Thruster Super NUT Replaces DC Brake Pot Other Thrustor style Brakes Designed for Severe Duty Service NO RECTIFIER SMOOTH Set /release SQUEEZING NO POUNDING Unlimited duty cycle Actuator AC (or DC) MOTOR Weston Type Mechanical Load Brake Weston Type Mechanical Load Brakes What happens when Gearing fails? The Load will fall! Even with a Mechanical load brake! HOW DOES IT WORK? MOTOR has to DRIVE to load both UP and DOWN 4

5 Mechanical Load Brakes Rope Drum Brakes 1. 2nd Holding Brake 2. Helps share work of the main Holding brake 3. May Hold load if first brake doesn't 1. GENERATES HEAT IN the Gearbox 2. Worn Lining debris contaminates OIL 3. Can Mask failed Main Brake 4. No Help if Gears fail Designs available on some Package hoists For SPECIAL applications requiring a second HOLDING BRAKE Big Crane Drum brakes Magnetorque Eddy Current Brakes How Do they work Why / Where used? Applicable control Schemes 5 step Full Magnetic Hoist Static Stepless Advantages Competitors Stromag Eaton Dynamatic Magnetorque (Eddy Current Brake) Sizes / Model # SHOE type HOLDING BRAKE Single Shaft Double Shaft Foot Mtd Motor / Flange Mtd Brake Rectifier Magnetorque Brake 5

6 1 NAME THE BRAKE 2 Dynamic Braking = Energy Generation 4 Energy Generation = DYNAMIC BRAKING 3 5 GENERATOR = MOTOR Gravity / Wind / Force IN GENERATOR Electricity OUT Electricity IN MOTOR ANTI GRAVITY or FORCE OUT DYNAMIC or Regenerative Braking STATOR FIELD Squirrel cage motors ROTATES 60 HZ MOTOR ROTOR 2 Hz = 3600RPM 4 Follows & tries Hz = to 1800 catch RPM 6 Hz = 1200 RPM 8 Motor Hz stator = 900 RPM 2 Hz = 1800 RPM Electrical Stator field will either PULL the rotor around as a MOTOR 2 Hz = 900 RPM OR The rotor with the aid of Gravity will PUSH the Magnetic Field around the Stator GENERATING ELECTRICTY instead of USING IT and the Stator will hold the rotor Back acting like IF the arotor BRAKE LEADS or is pulled against the the STATOR rotation, POWER is Generated and REGENERATED back to the line and BRAKING occurs WHAT DO YOU NEED FOR REGENERATIVE BRAKING TO OCCUR? STATOR FIELD ROTATING TEST QUESTION NO Electrical Power to the motor = NO REGENERATIVE BRAKING HZ Inverters DB Module 2 speed & AFD Hoists use DYNAMIC BRAKING / REGERATIVE BRAKING REGENERATED ENERGY IS BURNED OFF AS HEAT Resistor Banks on Large HP 6

7 LATEST VFD DRIVES ELECTRIC CHAIN HOISTS TYPICAL BRAKES TODAY Regenerative Speed Control Braking 1. Use regenerated energy off the DC BUSS to drive other motions 2. Convert Excess energy back into 60HZ AC and Pump it back into the line Optional Mechanical Load brake A few Brands Direct acting Electric Disc Type Load / Motor Brake FAIL SAFE TEST What did we learn? THANK YOU 1. Name 2 types of Holding Brakes. 2. Name 2 types of CONTROL BRAKING Means. 3. Name 2 reasons why A DC brake is superior to an AC Brake. 4. What are 3 weaknesses of using a Mechanical load brake 5. What is required for Regenerative Braking to work? 6. Which brakes will work if there is a power outage? 7. What are the 2 types of brakes required by ANSI /ASME? 8. What does Fail Safe mean? 9. Why don t Large capacity cranes use Weston type Mechanical load brakes? 10. Which Braking system is most likely to keep a load from falling. NOT JUST LIFTING THINGS, BUT ENTIRE BUSINESSES Mike D. James Vice President- Industrial Cranes Konecranes Inc. 7

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