Platform Lift Application

Application Description

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

Configuration:

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.

Column Strength:

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
63,025
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
17 in
NTwist = 41.48 in-lb × ( 17 in ) = .57o
1,235

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.

Jacks:

  • (3) 2.5-BSJ-IR 12:1/SSE-1/SSE-2/FA/15/S

Gearboxes:

  • (2) GB210 Type D

Shafting:

  • (2) LJ-8 17" OAL
  • (1) LJ-8 12" OAL

Couplings:

  • (3) P-2200-XX (½ - ½)
  • (5) P-2200-178 (¾ - ¾)

Motor:

  • 2 HP AC Motor 1750 rpm
Figure 1

 

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