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Weasler Cross and Bearing Kit Design

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Senior Design 

ME4930

Section PSV1

Donald Blausey, Dylan Dorava, Dakota Streck, and Justin Lorenz

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Overview

Cross and Bearing Kit

Sponsor: Weasler Engineering, West Bend, Wisconsin

Sponsor Contact: Kyle Matenaer, Weasler Test Engineer

    • Increase operating life to 200+ working hours
    • Reduce or eliminate maintenance

Key objectives 

    • Improved needle dimensions
    • Improved seal design
    • Utilize a new, high-performance lubricant

Recommended Solutions

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Primary Components of Interest

The cross and bearing kit consists of:

  • Cross
  • Bearing-caps
  • Bearing-needles
  • Seal
  • Lubricant

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Project Objective

  • Identify factors limiting lifespan
    • Components with excessive wear
  • Apply engineering principles to evaluate components
    • Stress analysis calculations 
    • Simulation software
  • Create a solution
    • Change the size and number of needles
    • Change the seal design
    • Improve lubrication
  • Verify results

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Project Constraints

Standardize dimensions for Weasler Cross and Bearing kits

-Fit within the 35 Series size envelope

Increase the lifespan Cross and Bearing kit

-Reliable for 200+ hours

Reduce the customer’s service interval

-Maintenance interval greater than 50 hours

-Stretch goal to achieve maintenance free operation for life

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Testing Criteria

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Problem Solving Approach

  • Identify customer requirements
  • Translate to engineering characteristics
  • Re-design key components 
  • Evaluate solution

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Overview of Recommended Solution

  • New Lubrication
    • Schaefer’s SynForce 219 grease
  • Optimized Rollers and Overall Geometry
  • Re-designed lip
    • Teflon
    • No metal-on-metal contact
    • Less friction

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Methodology

  • Optimized calculator for desired lifetime
    • ISO 281 Standard Roller Bearing L10
  • Compared results to a MESYS software analysis
    • Widely used industrial solver
  • Lifetime estimations within 1% of each other

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Source: https://www.mesys.ag/

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Force Calculations

  • Purpose: Translate dynamic torque to radial force on the bearing cap during operation
  • Dynamic torque, Td = 8,000 inch-lbs (903,878 N-mm)
  • R = distance from center of rotation to center point of a needle
  • Radial force, Fr = 13,500 N

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Needle Dimension Calculations

  • Purpose: Calculate fatigue (lifespan) ratings
  • Accounts for trunnion, needle and bearing geometric factors, including
    • Needle length, diameter & quantity
    • Displacement angles within bearing cup
    • Constants from ISO 281 testing standards
  • Computationally optimized to generate ideal needle properties
    • Ideal needle diameter = 4.73 mm
    • Ideal needle quantity = 14

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Working Lifespan Calculation

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Verification

  • Two verification methods:
    • MESYS Roller Bearing simulation tool
    • Standard mathematical calculations
  • Inputs came from ISO 281:2007 Roller Bearing standards
  • Both methods agreed that the recommended modifications would lead to 235+ working hours

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Finalized Needle Design

  • Reconfigured dimensions
    • Diameter = 4.73 mm
    • Quantity = 14 needles
  • Key Benefits
    • Constant or reduced stress concentrations
    • More evenly distributed stresses
    • Less material wear

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Finalized Grease Recommendation

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Finalized Lip Seal Design

  • Features:
    • Two lips inclined inward 45°, 1 lip inclined 45° outward
    • Constructed of 100% PTFE
      • Easier to manufacture
    • Eliminated steel reinforcement ring
    • No change needed to diameter of the cross

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New Lip Seal Benefits

  • New Geometry Benefits
    • 2nd lip inclined inward retain grease better
    • No change in cross diameters
  • PTFE Benefits
    • Low coefficient of friction (0.1) forms a tighter seal
    • -400 °F to 500 °F operating temperature
    • 39% stronger than NBR
      • Tensile strength = 25 MPa
    • Superior resistance to acids, alcohols and UV light

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Conclusions

  • Final Design Solution
    • Provides 235 working hours
    • Maintenance free – no need to regrease
    • Fits within existing yoke
  • Increased customer satisfaction
    • Improved performance
    • Less downtime
    • Less frequent replacement

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Environmental Impacts

No increase in toxicity

    • Pure PTFE is recyclable vs NBR + steel ring that must be separated first

Recyclable lip seal

    • Free of toxic heavy metals
    • No regreasing = less grease consumed
    • Passes the EPA’s strict Acute Toxicity Testing standards
    • Low marine organism toxicity

Environmentally-friendly grease

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Recommendations

Accomplishes design objectives

Adheres to design constraints

Implement design recommendations

    • Provide 235+ maintenance-free working hours

Begin prototyping for physical lab testing