Mechanical torque limiter 4-970-G

frictionwith clutch functionsteel

Torque adapter set 9 pcs (4-970-G) provides preset torque adapters from 0.1 to 0.6 Nm for 4 mm bits, enabling precise torque control for manual work and low-speed power-tool applications. The set contains adapters, bit adapters and holders supplied in a plastic quadro box for safe storage and transport.

Key features

• Preset torques, content: see parts list. Tolerance ±10% (factory certificate on request)
• Adapter body diameter Ø 8 mm, length 22 mm (without shank)
• Hex shank 1/4 inch — in combination with power tools limit max. speed 100 rpm
• Bit magnetic holder 4.0 mm
• Material: alloyed steel, hardness HRC 43–48
• Includes 2 bit adapters 1/4" to 4 mm in plastic quadro box
• 1-piece aluminium bit holder, 1-piece chrome-plated steel bit holder
• Packaged in plastic quadro box (91 x 43 x 15 mm)
• Weight (set): 108 g

Content

• 4-971 torque adapter 0.1 Nm for 4 mm bits
• 4-972 torque adapter 0.2 Nm for 4 mm bits
• 4-973 torque adapter 0.3 Nm for 4 mm bits
• 4-974 torque adapter 0.4 Nm for 4 mm bits
• 4-975 torque adapter 0.5 Nm for 4 mm bits
• 4-976 torque adapter 0.6 Nm for 4 mm bits
• 4-564 bit adapter 1/4 to 4 mm bits, length 42.5 mm
• 4-566 bit adapter 1/4 to 4 mm bits, length 25 mm

Area of application
Turn a 4 mm C4 bit and a holder into a precise torque tool. The adapters are designed for applications requiring small preset torques (electronics, quick-change systems, robotic stations, aerospace, medical, bench work). The click indicates when the preset torque is reached and prevents overtightening. When loosening screws there is no torque unlocking (resulting in approx. 30% higher torque when loosening). Primarily suitable for manual operation; for power tools limit to max. 100 rpm and avoid high click repetition.

Technical description
The adapters are tested according to DIN EN ISO 6789 (manually operated torque screwdriving tools) and specified with a tolerance of ±10% for at least 20,000 clicks. Users should check torque values periodically with a torque meter. Function principle: torque is limited by locking the ratchet in the bushing sleeve. The patented system consists of a hollow core shaft and a damping cylinder; the core shaft moves the mobile ratchet and the damping cylinder with a slot allows the spacer sleeve to slide on the core shaft. When applied torque exceeds the preset value the core shaft becomes inactive so continuous tension is no longer increased and the preset torque is maintained.

Technical specifications

• Model: 4-970-G
• Brand: Bernstein
• Number of pieces in set: 9
• Torque range: 0.1–0.6 Nm (preset values as listed in content)
• Adapter diameter (body): Ø 8 mm; adapter length (without shank): 22 mm
• Shank: 1/4 inch hex
• Bit holder diameter: 4.0 mm (magnetic)
• Material: alloyed steel, hardness HRC 43–48
• Packaging: plastic quadro box (91 x 43 x 15 mm)
• Weight (set): 108 g
• Test standard & durability: DIN EN ISO 6789, tolerance ±10% guaranteed for at least 20,000 clicks
• Operation note: primary manual use; with power tools limit to max. 100 rpm and avoid high click repetition; torque values should be rechecked periodically with a torque meter