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From Hartzell Engine Technologies

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The New M-Drive is the best lightweight starter designed specifically for Large-bore Continental Engines equipped with TCM starter adapters.

The M-Drive Starter Will Not damage your TCM Starter Adapter – Read More

With a proven 2.8kw high torque motor, the new M-Drive can start even the hardest cranking large bore TCM engines while safely disengaging from the starter adapter.

The “TCM Starting System” consisting of both a starter motor and a TCM Starter Adapter has been a very successful design for many years. Legacy (heavy, direct drive) starter motors from Delco, and Hartzell (formerly Kelly) (Prestolite & Energizer) have provided trouble-free service oftentimes through engine TBO. Recent market demands have stressed higher performance, lighter weight, longer design life, and lower current draw. Twenty-first century technology allows these improvements in the starter motor… but, that is just one-half of the TCM starting system. Powerful high strength permanent magnet, gear reduction motors have been designed to satisfy these market demands, but the biggest challenge has been developing a starter that can spin freely providing minimal back torque.

With the TCM starter system a key operating characteristic is that once the engine starts, it is necessary for the starter motor shaft to ‘turn backward’ only slightly to release the wrap spring tension and disengage the starter motor from the TCM starter adapter. If the motor resists reverse movement, the wrap spring tension is maintained on the starter adapter drive shaft after the engine starts causing excessive wear of the spring & shaft, eventually resulting in slippage or catastrophic damage requiring removal and overhaul of the TCM starter adapter. Repair or replacement may cost several thousand dollars.

Having been the OE starter motor supplier for 25 years, Kelly was aware of these requirements and designed the M-Drive lightweight starter to perform as successfully as its larger predecessors. Reducing the reverse torque to near zero was accomplished by designing an in-line solenoid that electrically connects the starter motor to the starter adapter drive shaft. Consequently, when the ignition key is released at engine start the solenoid completely disengages, immediately releasing the wrap spring drive tension, thus allowing the starter adapter drive shaft to rotate freely without damage.

No other lightweight gear-reduction starter has this low back-torque feature which precludes damage to your TCM starter adapter by the starter motor. When you are looking for a new starter for your TCM engine, ask for the M-Drive from Hartzell.

It is available in 12 volt (MRZ-7000) and 24 volt (MRB-7000) models and is FAA certified and PMA approved.

  • PMA – FAA Approved
  • Weight 7.5 lbs.
  • No Back-Torque – Drive Shaft spins free
  • Protects All Continental Adapters
  • 2 Year Warranty
  • No Bendix – Internal solenoid
  • Reliable Disengagement
  • Saves Installation Time with a Direct TCM Factory Starter Mount (No Clearance Issues!)
  • Aviation Designed & Developed -
  • No Automotive Aftermarket Parts Used!
  • Low Current Draw
  • Environmentally Tested – Under the most extreme conditions
  • 12 volt or 24 volt
  • Superior Duty Cycle
  • Powerful Permanent Magnet
  • Motor – High Torque
  • TBO Starter – Capable of providing Maintenance Free service to your engine’s TBO… and beyond.