# Analysis of Acme Stub Screw in a Jack Mechanism

## Data Analysis Questions:

a. What are the pitch, lead, thread depth, mean pitch diameter, and helix angle of the screw?

b. How can we estimate the starting torque for raising and lowering a 5000 lb load?

c. If the screw is lifting a 5000 lb load at the rate of 4 ft/min, what is the screw rpm and the efficiency of the jack under this condition?

d. Will the screw overhaul if a ball thrust bearing is used in place of the plain thrust collar?

## Answers:

I'm pretty sure it's c but I may be wrong.

When analyzing the data provided regarding the Acme stub screw in a jack mechanism, we need to determine various parameters such as pitch, lead, thread depth, mean pitch diameter, and helix angle of the screw. Additionally, we must estimate the starting torque for raising and lowering a 5000 lb load, calculate the screw rpm when lifting the load at a specific rate, and evaluate the efficiency of the jack under those conditions. Finally, we need to assess whether the screw would overhaul if a ball thrust bearing is used instead of the plain thrust collar.

**a. Determining Pitch, Lead, Thread Depth, Mean Pitch Diameter, and Helix Angle:**To calculate these parameters, we need to consider the major diameter of the screw, coefficients of running friction, and the known mean diameter of the thrust collar. With the given information, we can apply relevant formulas and equations to determine the pitch, lead, thread depth, mean pitch diameter, and helix angle of the screw accurately.

**b. Estimating Starting Torque for Raising and Lowering a 5000 lb Load:**The starting torque for raising and lowering a 5000 lb load can be estimated based on the friction coefficients provided, the weight of the load, and the known running friction values. By considering the starting friction assumption and the type of load, we can calculate the starting torque required for these operations.

**c. Calculating Screw RPM and Efficiency of the Jack:**When the screw is lifting a 5000 lb load at a rate of 4 ft/min, we can determine the screw rpm by considering the load, the lifting rate, and the mechanical efficiency of the system. By calculating the screw rpm and efficiency under these steady-state conditions, we can assess the performance of the jack and the screw mechanism accurately.

**d. Assessing Screw Overhaul with Ball Thrust Bearing:**To evaluate whether the screw would overhaul if a ball thrust bearing is used instead of the plain thrust collar, we need to compare the frictional forces acting on the screw in both scenarios. By considering the negligible friction of the ball thrust bearing, we can determine the potential impact on the screw's operation and overall performance. In conclusion, the analysis of the Acme stub screw in a jack mechanism requires a comprehensive examination of various parameters and factors to ensure optimal performance and efficiency of the system. By accurately calculating the pitch, lead, torque, rpm, and evaluating different components like thrust bearings, we can make informed decisions regarding the design and operation of the jack mechanism.