Product Overview

Materials

4

1

2

6

5

3

16

15

14

13

12

10

11

8

9

7

Diagram 1

Handle
Main Casing
Forward / Reverse Switch
Screwdriver Hex Output / Ring Gear
Motor Casing
Motor
Spring
Locking Gear

9. Pivot Button

10. Casing Screws

11. Pivot Screw

12. Locking Pin

13. Washer

14. Planetary Gears

15. Planetary Carriers

16. Sun Gear

Product Structure

Diagram 2

Pivot Mechanism

The pivot mechanism works with five main components, the main casing [2], the pivot button [9], spring [7], the locking gear [8], and a screw [11] to secure the assembly (Refer to Diagram 1).

When the button is unpressed, the spring exerts force that pushes the pivot button outward, causing its teeth to contact with the casing, locking rotation. The locking gear is also pulled inward, causing its teeth to contact the casing.

When the button is pressed, and the pivot button is pressed inward, the teeth unlock with the casing into this free pivoting groove, allowing the screwdriver to pivot freely. The locking gear is also pushed outward, unlocking its teeth from the casing.

This is the Locking Gear [8] and a clear view of how the teeth mesh to the handle teeth

Crucial pivoting area / groove

Power / Manual Mechanism

This is the Locking Gear [8] slotting into the handle

This is the pivot button [9] and the spring [7]. The pivot button also meshes with the handle. When pushes far enough the teeth unlock in the similiar way to the locking gear [8].

The power / manual mechanism works by pushing and pulling a ring gear that connects the driven planetary carrier (the output of the epicyclic gear system) to the ring gear / outer casing.

This connection made between the two gears, the carrier and the ring, causes the carrier to effectively work against its own direction of torque, not allowing it to rotate. This means there is no output torque, because it is stuck, disabling the output hex screwdriver head.

This also allows the user to use it manually, as the output hex cannot be turned because the hex screwdriver head is now rigid with the ring gear / outer casing. The head can neither be an input nor an output.

Unlocked Gear Train

This is the Unlocked State of the Gear Train, meaning the carrier can output freely. Pay close attention to the height of the white ring gear around the carrier. Notice how IT IS NOT meshed with the carrier

This is the symbol denoting the gear train can move freely, and can be driven by the motor in powered mode.

Locked Gear Train

This is the Locked State of the Gear Train, meaning the carrier is fixed to the ring gear. Pay close attention to the height of the white ring gear around the carrier. Notice how IT IS meshed with the carrier.

This is the symbol denoting the gear train cannot move freely, and is in manual mode.

Switch Mechanism

The switch mechanism is mechanical as opposed to electrical in that it switches the direction of the screwdriver output by switching the connections to the battery, switching the polarity on the motor.

The switch, in the off position, disconnects the battery. In one direction, the leads make a connection to the battery, causing it to turn one way. When switched, the connections to the battery switch, reversing the polarity, therefore reversing the direction of the motor.

Motor

Connections to Battery

Drawing and corresponding Basic Circuit Diagram to represent reversing polarities

Design for Manufacture and Assembly (DFMA)

Locking Motor Pin

The first mistake-proofing is categorized as "Prevention"; the Locking Pin that secures the entire gear assembly in the ring gear / casing. It prevents the motor from being removed from the gear system as well, preventing failure of the gear system. It also prevents the gearbox from falling apart inside the casing from general movement and usage.

Unlocked State, allowing the motor to be pulled out

Locked State, locking the motor to the casing

Pivot Restriction

The second mistake-proof is also categorized as "Prevention"; the Pivot Mechanism is designed in such a way that the screwdriver cannot be extended past 180° because of the physical limitation of the locking gear to the slot in the handle. This prevention of overextension saves the wires that provide battery power to the motor; repetitive overextension could damage these wires and destroy the tool.

Full extension State 1

Full Extension State 2

The gear teeth in both the Pivot Button [9] and Locking Gear [8] don't allow for overextension.

The third mistake-proof is also categorized as "Prevention"; the main casing is designed in a way that cannot be assembled incorrectly. Screw holes line up together and ridges line up. This ensures that the main casing, pivot mechanism, and handle are assembly correctly.

Casing Design

Opened Main Casing

Closed Main Casing

Black and Decker Li2000

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