The document describes the development of a linear actuator with interchangeable gearbox modules providing gear ratios of 30:1, 60:1, and 100:1. The linear actuator is intended for use in actuating the fingers of a prosthetic hand. It consists of a DC motor, screw-driven plunger, and gearbox module that can be changed to vary the torque output. The gearbox modules are designed with multiple gear stages and specifications are provided for the gears used in the 30:1 and 60:1 ratio designs. A worm and worm gear configuration is also proposed to provide additional gear ratios.

1. LINEAR ACTUATOR
Debanjan Mandal
(B. Tech Mechanical, PG Diploma Advanced Manufacturing)

2. Linear Actuator Development
Aim:- Developing Linear Actuator with interchangeable gearbox module with reduction ratio
30:1, 60:1 and 100:1
Approach:
Design Constrains
Dimension
Application
Technical Specifications
12.5mm
44 mm
22.5 mm
Prosthetic Hand Finger Actuation
• Stroke Length-30mm
• Gear Ratios
➢ 30:1
➢ 60:1
➢ 100:1

3. 30:1 Linear Actuator
Calculation= (28*31*31*39)/(12*14*13*16)= 30.03:1
➢ Module-0.16
➢ Pressure Angle-20
Arrangement of gears in the gear box
(Cylinders of Diameter equals to pitch circle diameter are
used to visualize the arrangement)
Side View
INPUT GEAR
OUTPUT GEAR

4. No. of Teeth=12
Pitch Diameter=1.92mm
Outer Diameter=2.24mm
Inner Diameter=1.52mm
No. of Teeth=28
Pitch Diameter=4.48mm
Outer Diameter=4.8mm
Inner Diameter=4.08mm
No. of Teeth=14
Pitch Diameter=2.24mm
Outer Diameter=2.56mm
Inner Diameter=1.84mm
No. of Teeth=31
Pitch Diameter=4.96mm
Outer Diameter=5.28mm
Inner Diameter=4.76mm
No. of Teeth=13
Pitch Diameter=2.08mm
Outer Diameter=2.4mm
Inner Diameter=1.68mm
No. of Teeth=31
Pitch Diameter=4.96mm
Outer Diameter=5.28mm
Inner Diameter=4.76mm
No. of Teeth=16
Pitch Diameter=2.56mm
Outer Diameter=2.88mm
Inner Diameter=2.16mm
GEAR SPECIFICATIONS

5. No. of Teeth=39
Pitch Diameter=6.24mm
Outer Diameter=6.56mm
Inner Diameter=5.84mm
Gear Box Module for 30:1 Ratio Actuator
Rendered version

6. 30 mm
Plunger
Screw
Fasting Screw
Gear Box
Bearing
DC Motor
Top to Bottom:
▪ Top View of Actuator
▪ Retracted Mode
▪ Extended Mode
Changeable
Rendered Model

7. 60:1 Linear Actuator
Calculation= (31*36*36*39)/(12*11*13*15)= 60.87:1
➢ Module-0.16
➢ Pressure Angle-20
➢Circular Tooth thickness- 0.251328mm
➢Whole Depth-0.36mm
Arrangement of gears in the gear box
(Cylinders of Diameter equals to pitch circle diameter are
used to visualize the arrangement)
OUTPUT
INPUT
Side View

8. No of teeth= 12
Pitch Circle Diameter= 1.92mm
Outer Diameter= 2.24mm
Inner Diameter= 1.52mm
No of teeth= 36
Pitch Circle Diameter= 5.76mm
Outer Diameter= 6.08mm
Inner Diameter= 5.36mm
No of teeth= 15
Pitch Circle Diameter= 2.4mm
Outer Diameter= 2.72mm
Inner Diameter= 2mm
No of teeth= 36
Pitch Circle Diameter= 5.76mm
Outer Diameter= 6.08mm
Inner Diameter= 5.36mm
No of teeth= 13
Pitch Circle Diameter= 2.08mm
Outer Diameter= 2.4mm
Inner Diameter= 1.68mm
No of teeth= 31
Pitch Circle Diameter= 4.96mm
Outer Diameter= 5.28mm
Inner Diameter= 4.56mm
No of teeth= 11
Pitch Circle Diameter= 1.76mm
Outer Diameter= 2.08mm
Inner Diameter= 1.36mm
GEAR SPECIFICATIONS

9. No of teeth= 39
Pitch Circle Diameter= 6.24mm
Outer Diameter= 6.56mm
Inner Diameter= 5.84mm
Gear Box Module for 30:1 Ratio Actuator

10. GEAR
BOX
Only Gear Box module has to be changed to change the torque of the actuator
30:1
60:1
100:1

11. Linear Actuator With Worm and Worm Gear box
Check for gear arrangements
2-Stage Reduction
2
1
Worm Gear
No. of Teeth-30
Module-0.16
Pitch Diameter-4.8mm
Helix Angle-5.05
Worm
No. of Threads-1
Gear Ratio= 30/1= 30:1