Platform Lift Application
A manufacturer is looking for linear motion systems that can periodically raise and lower a cylindrical mixer eight inches during the mixing cycle to allow product testing to insure product quality and consistency. The cylinder weighs 1,700 lbs and is mounting on a movable cart allowing for the final product to be moved to a dispensing station. The customer wants a 4 times safety factor with respect to capacity. The solution for this application involves worm screw jack systems.
Step 1: Determine Specifications
- Single motor and drive
- The load will be in tension
- Total travel 8 inches
- 4 times safety factor
- 8 inches in 5 seconds
Step 2: Analysis
To minimize the size of the motor drive, a Ball Screw jack will be used. Based on the mounting frame, the inverted rotating configurations will be used.
The jacks will be loaded in tension, therefore column strength does not need to be considered.
Speed and Horsepower:
Using a standard 1750 AC Motor and the 2.5HL-BSJ with the 12:1 gear ratio, full travel would be reached in 3.5 seconds. Using the horsepower formulas on page 15 of our Worm Gear Screw Jacks Catalog, a 2 HP AC motor running at 1750 rpm will be adequate for the requirements.
|HPper jack =||.0244 in-lb × 566 lb × 1,725 rpm||= .38 hp / jack|
|HParrangement =||.38 hp per jack × 3 jacks||= 1.55 total hp|
|.9 × (.9)2|
LinkJac Line Shafting:
The longest center to center distance between the jack and gearbox is 24 inches, leaving a shaft length of 17 inches. Using the formula on page 189 based on Torsional Twist, the proper Line Shafting to use would be the LJ-8.
|NSpeed =||.6692 × (||π||)2 × 3.895 × 105 = 44,547 rpm|
|NTwist =||41.48 in-lb × (||17 in||) = .57o|
Step 3: Product Selection
Create a Reference Number for the Assembly
From page 31, create reference numbers for the following: three 2.5 ton ball screw jacks, inverted rotating configuration, 12:1 worm gear ration, 15 inches "L" dimension.
- (3) 2.5-BSJ-IR 12:1/SSE-1/SSE-2/FA/15/S
- (2) GB210 Type D
- (2) LJ-8 17" OAL
- (1) LJ-8 12" OAL
- (3) P-2200-XX (½ - ½)
- (5) P-2200-178 (¾ - ¾)
- 2 HP AC Motor 1750 rpm