Ladder Design
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Date
2017-12-06
Authors
Gadient, Shaun
Li, Ang
Mitchell-Dueck, Joshua
Sekhon, Amritpal
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Abstract
The design of an adjustable fire truck access ladder which has a minimized profile when stowed and can be quickly adapted for a range of custom fire truck sizes is required by the client, Fort Garry Fire Trucks. The ladder must incorporate slip-resistant components, have a maximum stowed profile of 8”, and must support a 500 lb static load with no deformation, using a safety factor of 2. The bolting of the ladder to the body of the truck is not considered in this report. In the selected design, the upper and lower ladder sections are connected by a bracket bolted at the bottom of the upper ladder section. The bracket houses a pivot point at which the lower ladder section rotates on a Grade 8 steel bolt, housed in a nylon bushing, to deploy and stow. Two position control springs, attached on either side of the ladder between the bracket and the lower ladder section, hold the lower ladder section in the deployed or stowed position. The ladder is connected to the body of the truck at two points in the upper ladder section. The ladder is connected to a hinge point in the upper connection bracket on its right and left runners, using a Grade 8 steel bolt housed in a nylon bushing. The ladder also connects on both sides to a hinge point attached to an A-frame mount, connected to the lower connection bracket. The lowest factor of safety of 2 is in the upper connection bracket, while the runners of the upper ladder section have a factor of safety of 31.17 for one load case. The total weight of the ladder is 115.39 lb, which will be reduced for shorter ladders. All brackets in the design are laser cut from A36 Hot Rolled Steel of varying thickness, as are the links in the A-frame mount. The ladder runners are saw-cut aluminum 6061- T6. The slip-resistant ladder steps are sourced from Cast Products Inc., a rotary latch to mechanically lock the ladder in its stowed position is sourced from Southco, and a position control gas strut to...