To receive the most up-to-date product availability, pricing and delivery options, enter your zip code or log in to your account
Zip Code should not be blankEmail and Password should not be blank
Enter Delivery Zip Code
or
Log In
TELL US MORE
Are you currently located in California?
8 characters minimum
One number
One lowercase letter
One uppercase letter
One special character (!@#$%&*)
Password cannot contain space
Pursuant to CA SB 478, if you are located in California, Airgas cannot display your product pricing until all items have been added to your shopping cart so that we can calculate all applicable fees, including, but not limited to, shipping and handling fees.
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
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.
