Podium Pressure Locking Safety System Richard Cavanagh, Piragash Selvakumar, Ricky Eatough & Mohit Miyanger Queen Elizabeth’s Boys School, Barnet
The Issue Working at height is the biggest killer in the construction industry. In 2016/17, 30 fatal injuries occurred concerning construction. In 2016/17, 25 fatal injuries occurred relating to working at height. The main reason for this was that workers were failing to lock their wheels.
The Problem When needing to work on ceilings and high walls in a construction project, workers are required to use a podium steps and require the brakes of the podiums to be applied before entering. Workers fail to lock the wheels due to many psychological factors such as trying to complete as many tasks as possible. Main Question: Can the human aspect of applying the brakes be removed?
Brief To design an attachment or alteration to PAS 250 compliant podium steps that: • Removes the need for workers to apply the brakes consciously • Should be intrinsic and automatic • Must require the worker to get off the podium to remove the brakes and to move the podium again • Stops podium steps from toppling when wheels/feet are directly over floor boxes • Stops operatives from skating
Research Two sites visited in Canary Wharf: 1. Deutsche Bank Project 2. Barclays Bank PAS 250 Regulated Podium Scissor lift Platform Step Raised false floor Wheel locking mechanisms
PAS 250 1000 Power towers Pecolift • Standards legislation Podium unit • Unlocked by deliberate actions • Corrosion protection according to BS 8620 • Percentage elongation after fracture of load-bearing components Materials • Dimensions of floor boxes • Aluminium • Mild Steel • 70-130mm (standard 85mm)
Site Visit Questionnaire Why do injuries occur? How many & How serious are they? • Podium ‘surfers’ and ‘skaters’ – ‘laziness’ . • Walk off without locking wheels. • Several serious injuries. How are workers alerted to the need to lock the wheels? (both groups) • Safety managers walk round the site. • Notices at the site informed workers using podiums that ‘brakes to be used at all times when in use’ . • Stabilisers not mandatory – trip hazards. Variation of working platforms: • A large variety of platforms were in use such as: • Delta deck. • PECO lift - Preferred method • Locks automatically • Easy to adjust height • Large – fitting through doorways • Heavy – hard to take up stairs • Expensive • ECO lift. • MEWPs (mobile elevating work platforms). • Scaffold towers. • Podium steps. • Standard stepladders.
Product analysis – Kick stool • Generic kick stool as found in shops: • 3 Spring loaded castors • Auto locking handle • Rubber seal • Difficult to topple
Specification • The specification had to be adjusted due to the different types of research, such as the British Standards legislation. • This can be seen with specification point F3 that requires the worker to manually remove the brakes of the podium steps. • The performance section of the specification has been directly influenced by how we saw the podium steps being used during our site visits to the Clifford Chance and Barclays Bank buildings. • The ergonomics section has been deduced by using anthropometric data to work out what sizes we needed to make certain parts of the product in order to make sure they were not uncomfortable for the user or were too small for the user to use. • The safety of the workers was of the utmost importance when creating the specification as it was the main problem that arose in the situation.
Conceptual Ideas A large block locks the wheel and comes into contact with the ground after the user releases the handle Before Pressure Applied The block is pivoted through attachment to the main frame. After Pressure Applied Idea 2: Idea 1: Positive: Positive: Prevents surfing, skating and floor box Easily locks wheels. dangers. Negative: Negative: Not collapsible, easy to break Large and not collapsible. Can still go through floor boxes .
Conceptual Ideas A spring loaded mechanism is used in each of the four legs which can be easily attached on and Weight of operative causes podium to lower. off. A large surface area on the The adaptations can bottom means that it will Bar rests on the ground - Large surface area on the ground – clip on, meaning that it not damage the floor and Spring-loaded will be easy to prevents toppling. will provide even pressure. mechanism in wheels transport and carry. allow free 360 degree Idea 3: motion. Idea 4: Positive: Prevents surfing as the wheels will lock. Final Idea based off this design Positive: Negative: Auto-locks wheels. No safety mechanism: Floor box fall protection. Roll in other direction when worker steps off. Negative: Large to carry through doorways and hard to transport.
First Development Developed from concept 4 Trapezoidal prism for surface area Positives Large surface area Removeable Simple Negatives Too much material Difficult to transport
The Solution Developed in UCL ▶ Trapeziums to shrouds ▶ Spring Loaded Wheel Mechanism ▶ Small amount of material used ▶ Lightweight ▶ Can be retrofitted ▶ Intrinsic design ▶ Automatically Locks wheels ▶ Large shroud size ▶ Prevents podium toppling in Gromit & ▶ Floor boxes Pin mechanism ▶ Manageable height ▶ Width right for hands ▶ Two points of contact
Mechanism Animations Close Up Complete Mechanism Close-up Complementary Shapes
CAD Outer tube Two points of contact Main compression spring Inner tube Variable Spring Tension Shroud Cap Shroud Crutch Mechanism
Manufacture 4 3 2 1 5 10 11 9 6 7 8
Testing Testing was carried out on the prototypes we manufactured and not on a full scale working • platform, so the scale of our tests had to be reduced to suit the prototypes. • The prototypes were assessed via 3 different tests. • Test 1 : Activation of Brakes. Required 45.5 kg to activate the pin mechanism. Test 2 : Deactivation of Brakes. • Test 3 : Movement of Prototype. 19.8 seconds to walk in a circle with a radius of 2 metres and • was successfully moved 20 metres forward. • These tests allowed us to find out how well the prototype followed the specification. Test 1 Test 2 Test 3
Costing Prototype Industrial Manufacture Element Quantity Dimensions (mm) Component Cost (£) Source Quantity & Element Component Cost (£) Source 4 10 diameter Inner rods 8.41 Metals4U Dimensions (mm) 1000 Steel rod 50.8 diameter Outer steel 25.91 Steel Tubes Direct Steel tube 1.5 thickness tubes 4 30 diameter Inner steel 13.69 Metals4U 1200 1.5 thickness tubes 10 diameter Inner rods 5.88 B&Q Steel rod 800 Steel tube 1000 30 diameter Inner steel tubes 14.71 Steel Tubes Direct Steel tube 1.5 thickness 8 10 Crutch pins 0.21 Metals4U 800 50 Shroud mould 26.75 4D Model Making Materials Steel square Foam 600 1250 5 Crutch springs 6.99 Screwfix Steel 8 6 Crutch springs 2.37 Thespringstore 20 spring 7.5 20 diameter Springs 4.46 Cromwell Steel Steel spring 25 spring 3 Discs 0.66 The Metal Store 60 Sheet steel 4 20 Springs 7.66 Thespringstore 110 Steel spring 84 12.7 Shroud 21.07 Metals4U 1 thickness Discs 0.18 Metals4U Aluminium 1000 120 Sheet steel ingot 110 240 Discs 4.34 The Metal Store 4 100 Shroud 32.74 Metals4U 240 Aluminium Sheet steel ingot M10 Nuts 0.26 Cromwell Nuts 65.26 TOTAL M10 Washers 0.46 Tool Station Washers 111.49 TOTAL
Future Developments 5 Reduced shroud width Thinner sides Cast as one piece 1 2 Hinge Mechanism 3 4 6 Shroud Cap Reduced Shroud Width
Implementation & Future manufacture ▶ Retrofit to existing podiums: ▶ BS 8620 certification required for LLWP ▶ Meet PAS 250 specification ▶ Manufacture into new podiums: ▶ Pass all testing, as detailed in BS 8620 ▶ Developed in conjunction with Overbury ▶ Interest in immediate site implementation when available ▶ Utilising large network of suppliers and manufacturers ▶ Less Material – thinner, lighter ▶ Different shrouds for different trades ▶ Different quality/strength ▶ Adjustable tension springs for a longer life span
Podium Pressure Locking Safety System
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