## Power Screw Torque

Consider a square thread power screw can lift a 20 kN load with a 70% efficiency. If the lead is 0.01 m and the thread coefficient of friction is 0.05, how much torque (N∙m) is needed?

##
__
__**Expand Hint**

**Expand Hint**

The power screw’s efficiency is:

$$$\eta=\frac{Fl}{2\pi T}$$$

where
$$F$$
is the load,
$$l$$
is the lead, and
$$T$$
is the torque.

##
__
__**Hint 2**

**Hint 2**

The friction coefficient is not needed to solve the problem. It only exists to cause confusion.

The power screw’s efficiency is:

$$$\eta=\frac{Fl}{2\pi T}$$$

where
$$F$$
is the load,
$$l$$
is the lead, and
$$T$$
is the torque.

Notice how the friction coefficient is not needed to solve the problem. It only exists to cause confusion. Solving for torque:

$$$0.7=\frac{(20,000N)(0.01m)}{2\pi \cdot T}$$$

$$$T=\frac{(20,000N)(0.01m)}{2\pi(0.7)}=\frac{200N\cdot m}{4.396}=45.5\:N \cdot m$$$

45.5 N∙m

Similar Problems from FE Sub Section:

337. Power Screw

520. Power Screw Load

Similar Problems from FE Section:

135. Helical Spring

141. Tensile Strength for Springs

205. Compression Spring

206. Spring Force

265. Mechanical Springs

280. Joint Shear Stress

295. Planetary Gear

296. Roller Bearing

299. Ball Bearing

335. Spring Stretch

337. Power Screw

339. Compressing a Spring

341. Parallel Springs

343. Springs in Series

347. Bolt Diameter

371. Spring Compression

381. Series of Springs

384. Springs in Parallel

386. Compounding Springs

387. Spring Tensile Strength

388. Torsional Stress

392. Chrome Silicon Wire

456. Free Length Spring

458. Rivet Strength

478. Spring Stretching

480. Threaded Fastener Load

481. Max Tension Load

483. Fatigue Loading

484. Correction Factor

485. Mean Stress

486. Bending Stress

520. Power Screw Load

**Power Screws**337. Power Screw

520. Power Screw Load

Similar Problems from FE Section:

**Mechanical Design and Analysis**135. Helical Spring

141. Tensile Strength for Springs

205. Compression Spring

206. Spring Force

265. Mechanical Springs

280. Joint Shear Stress

295. Planetary Gear

296. Roller Bearing

299. Ball Bearing

335. Spring Stretch

337. Power Screw

339. Compressing a Spring

341. Parallel Springs

343. Springs in Series

347. Bolt Diameter

371. Spring Compression

381. Series of Springs

384. Springs in Parallel

386. Compounding Springs

387. Spring Tensile Strength

388. Torsional Stress

392. Chrome Silicon Wire

456. Free Length Spring

458. Rivet Strength

478. Spring Stretching

480. Threaded Fastener Load

481. Max Tension Load

483. Fatigue Loading

484. Correction Factor

485. Mean Stress

486. Bending Stress

520. Power Screw Load