Wegmans Bred Tray Lift Asist

Wegmans Bread Tray Lift Assist Design Review 2Wegmans Bread Tray Lift AssistGoal:Improve ergonomics for operator during the task of stacking loaded bread trays at the Wegmans Bakery

NeedsEnable good ergonomic practices in terms of lifting and body positionMeet Wegmans safety requirements in terms of mechanical operation and physical aspects Meet Wegmans requirements in terms of cleaning and food contamination risksEase of use for operatorThe unit should be durable and reliable SpecsMaintain a loading height at 33 inchesAllow for food to descend no closer to the floor than footAllow max load of 5 trays at 115 lbfAndUpdated Design

Whole Assembly

Updated Design Continued

Lift Tray Cart

Features:V groove wheelsRedesigned as skeletonCotter PinEnd Caps GussetsDouble Support BarLocating Wedge

Start3 way valve opens to pressure line Dolly and trays loadedAir goes into cylinderForks lower Forks lockForks raise to home positionRestart ProcessIs switch activatedButton pressedYesYesNoNo

Adjustable needle valveAir cylinder (2 inch bore and max of 125 lbs to lower requires ~40psi) 3 way valveEmergency relief ball valve

Air regulatorAir from lineMuffler

3 Way Normally Open to Atmosphere Push-Valve5th has been placed and is descendingLine is unpressurized

Switched pressed, wheels on groundLine is pressurized5th tray hasfully descended

Piston Pressurized, lowering piston slowlyForks lower, trays in contact with floor only

Filled until 40 psi is reached and cylinder is locked in down position

Open to ATM closed to pressurized lineCompressed air released to ATM

Open to ATM againPiston raises, acting as air damperDeflection and Force Analysis

Deflection seen by max force of Forks

WMax Deflection:

0.0171 inchDeflection and Force Analysis

Deflection seen by max force of top bar

FMax Deflection:

0.00166 inchProblems and Solutions from Last meetingDolly Sliding offHand GuardingPiston FailureFoot being crushed by forksEnd Caps on ForksBrush Guard SystemRemovable forks (use in place) Hard stop at 2 inches (normal use leaves 2.75 inch clearance)Updated Risks Updated Mitigations Springs failingMaterials not arriving on time/correct materialAir drop installationAir piston damper failingNot used correctlyor at all

Designed with factor safety BOM finished and ready to orderVerify with MikeDesigned with factor safety involvedAsked operators what they want/expectErgonomic AnalysisNIOSH Lifting Equation:When setting tray on ground: 1.7With Bread Tray Lift Assist: 1.4Analysis of only 36 inch and belowPercent improvement: 17.6%

Ergonomics ContinuedRelease button height: 45 inches from floorHeight based up elbow height for 95th percentile male according to ANSUR databaseTray stack height: 30-36 inches from floorBased upon height of hand at rest calculated from ANSUR databaseReduces bending at waistLower risk of back strainNo detriment to higher liftsAdditional suggestion: add anti-fatigue mat to floor where operator standsSafety FeaturesBright colored forks for visibilityPowder Coated YellowHard stop for forks at 2 inches above floorPrevent foot from being crushed in a failure situationRemovable forks removes collision hazard when device is not in useSimulated Floor Plan30301836OperatorBill of Materials

Next StepsProcurement of materialsRegulatorFloor LocationAir DropPlanning shop fabrication timeReceivingAir Cylinder Maintenance Build and Test