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Makita® Switch Unit (For Use With Cordless Drill)
Airgas Part #:MAK638144-2
Manufacturer Part #:638144-2
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$32.10
Each
$32.10
/Each
Item Details
- The Makita 638144-2 Switch Unit is an original equipment manufacturer (OEM) integrated electromechanical sub-assembly designed for Makita industrial cordless tools. It serves as the primary power modulation, user interface, and safety system, managing variable current flow, dynamic directional switching, mechanical latching, and terminal-to-battery connections. It features a factory-engineered "reversed wires" configuration to prevent cross-polarity faults during field installation.
Features
- Variable Amplitude Resistance (VAR) Speed Control: Enables deep modulation of tool RPM from 0 to maximum velocity based on trigger pressure to prevent work-surface marring and screw-head stripping.
- Dynamic Electric Braking Circuitry: Mechanically shorts the tool's DC armature windings upon trigger release to instantly collapse motor momentum and stop the chuck.
- Integrated Mechanical Direction Locking Lock-Out: Top-mounted slot links with Forward/Reverse change lever (Part #417880-1) to physically block trigger depression when set to neutral.
- Self-Contained Heat Mitigation: Embedded heat sink block inside the inner switch body dissipates heat during prolonged partial-throttle operations to prevent thermal runaway.
- Reversed Wires Configuration: Factory-engineered wiring orientation isolates low-voltage control signals from raw high-amp field currents and prevents cross-polarity faults during installation.
Specifications
- Manufacturer: Makita USA Inc. / Makita Corporation (Japan)
- Part Number (MPN): 638144-2
- Alternative Part Number Codes: 6381442, MK-638144-2
- Legacy Reference (Replaced Legacy Part): 650521-8 (Single C3SA-ML switch unit)
- Main Switch Body: Integrated C3SA-ML single-stage variable speed trigger housing
- Battery Interface Block Terminal: Type 643918-8 composite battery holder and connection shoe
- Internal Wiring Harness: High-flex, heat-resistant copper leads pre-soldered in a reversed physical orientation
- Nominal Voltage Support: 12V DC and 14.4V DC
- Maximum Transient Voltage: 18V DC
- Current Type: Direct Current (DC)
- Speed Modulation: Analog variable voltage output via Variable Amplitude Resistance (VAR) mechanism
- Internal Switch Contact Geometry: 4 Internal Terminals separating forward circuit gates from reverse braking gates
- Housing Resin: Injection-molded Glass-Fiber Reinforced Polyamide (PA6-GF30)
- Trigger Paddle: Unreinforced Polycarbonate/Acrylonitrile Butadiene Styrene (PC/ABS) blend
- Contact Metallurgy: Heavy-gauge Silver-Nickel (AgNi) or Silver-Tin-Oxide (AgSnO2) coated copper busbars
- Wiring Conductors: Multi-strand high-purity copper core with high-flex cross-linked polyethylene (XLPE) or PVC insulation rated up to 105°C (221°F)
- Terminal Clips: Beryllium-copper alloy on the battery receiver shoe (643918-8)
- Length: ~78 mm (inclusive of terminal blade extension)
- Width: ~42 mm (across variable speed heat sink fins)
- Height: ~55 mm (from base of battery holder to top of F/R rocker actuator platform)
- Net Weight: ~0.08 kg (80 grams / 2.82 oz)
- RoHS (Restriction of Hazardous Substances): Compliant
- UL / CSA Compatibility Guidelines: Built to meet safety criteria under UL 60745 and CSA C22.2 No. 60745
- Ingress Protection (IP) Equivalency: Built to meet internal dust-shedding demands equivalent to IP5X
Includes
- 643918-8 Battery holder
- 650521-8 Switch
- C3SA-ML Single without lock variable
Applications
- Compatible Makita Tool Models: - Makita 6217D / 6217DWDE (14.4V DC Heavy-Duty Industrial Cordless Drill/Driver, 1/2" Keyless Metal Chuck) - Makita 6237DWDE (14.4V DC High-Torque Cordless Drill/Driver, 1/2" Heavy-Duty Chuck) - Makita 6317D / 6317DWDE (12.0V DC Cordless Driver-Drill, 1/2" Standard System) - Makita 6337D / 6337DWDE (14.4V DC Cordless Driver-Drill System, 1/2" Industrial Framework) - Makita 6207D (12.0V DC Cordless Specialized Drill, Mid-Torque Output Variant)
- Metalworking & Mechanical Assembly: Running self-tapping fasteners into heavy-gauge structural steel frames or sheet metal ducting.
- Industrial Maintenance, Repair, and Operations (MRO): On-site facility maintenance teardown and rebuilds, pump maintenance, and electrical enclosure installation.
- Commercial Carpentry and Timber Framing: Fastening high-strength structural lag screws, drilling with high-diameter auger bits, and hole-saw cutting through dense engineered lumber.
- Automotive Repair & Manufacturing Trades: Installation of heavy internal brackets and components using mid-voltage high-torque portable drivers.
Product Attributes
Product Type
» Switch Unit
