Retractable Combine Ladder Assistive Technology

This could work for trucks, excavators, logging equipment like forwarders, skidders, slashers, mining trucks, tractors, harvesters, and any place a ladder needs to be raised and lowered 24 inches.

SBR20-1200mm Linear Guideway Rail Kit https://www.vevor.com/collections/linear-guide-rail or other slide mechanism 36 to 48 inches long

6-foot folding ladder type 1AA 375 lb capacity https://www.lowes.com/pd/Werner-7300-6-ft-Fiberglass-Type-1AA-375-lbs-Capacity-Step-Ladder/999921630 or other similar capacity ladder

10 feet of bar stock 3" wide 1/4" thick

4 feet of bar stock 1" wide and 1/4" thick

Hardware 1 3/4" u-bolts 1/4" threads; 6 mm x 20 mm long bolts; 1/4" x 1" bolts and nuts; 5/16" x 2" bolts and nuts; 5/16" x 2" bushings.

Tools: band saw or angle grinder cutting disc, drill and bits, wrenches, welder

Slide Rail Plates: Cut two pieces of bar stock 48-inches long for slide rail mounting plates. Lay the SBR slide rail on the plates flush at one end. Mark and drill the holes and fasten the rails to the plates with 1/4 x 1" bolts and nyloc nuts. Slide Bearing Plates: Cut two pieces of bar stock 8-inches long and drill holes to bolt the slide bearings flush at one end and spaced 1-inch apart on the plates as shown. Weld a 5/16" inner diameter bushing onto the opposite end of the slide bearing plates. 3/8" nuts can also be used as bushings for this purpose. This will be the hinge for attaching the ladder later on.

Use 1 3/4" u-bolts to fasten the slide rail plates to the existing combine steps grab bars. Position the bottom ends of the slide rail 5 feet above the floor. Make sure the distance between the slide rails is the same at the top and bottom so they are parallel with each other.

Slide the bearings onto the rails bushing-end-up. After the bearing plates are on the slide rails (bushing end up), weld or bolt a piece of 1-inch bar stock across the plates to connect them together. This will keep them sliding in unison and not bind up as the ladder raises and lowers.

Remove support leg from ladder. The support leg is the side of the ladder not intended for climbing on but holds the ladder steps upright while in normal use. Keep the folding hinge attached at the middle of the ladder steps. Grind the rivets and unscrew the bolts to remove the support leg from the hinges at top and middle to make the ladder steps 'one sided'. Dispose of the support leg.

Weld the middle hinge arm of the ladder so it no longer folds in half. Weld two 1-inch bars across the middle hinge to make it one rigid unit that moves in unison. Weld the middle folding point so it is a rigid arm instead of folding arm.

Bolt top of step ladder to slide plates. Use 5/16 bolts through the bushings on the top of the slide bearing plates to attach the top of the ladder. Flat washers between the bushings and the ladder will keep the ladder centered between the slides.

Bolt middle hinge arm to slide rail plates. Once the top of the ladder is fastened to the slide bearings, lower the ladder as far down as possible without the bearings dropping off the the slide rails. You will need to pull the bottom of the ladder away from the combine as you lower the top of the ladder. This provides the nice sloping steps for the worker to climb. Now that the ladder is positioned in the 'down' position, rest the middle hinge against the lower end of the slide rail plates. Weld a short section of bar stock onto the slide rail plate so the middle hinge can be bolted onto it. Drill holes in the bar stock and bolt the middle hinge arm to it.

Attach a chain or rope to the middle step of the ladder while in the down position. Attach the other end of the rope or chain to a hook near the equipment door. Pulling up on the rope lifts the ladder and swings the bottom end of the ladder tightly against the equipment. Once the ladder is raised, attach the chain or rope to the hook near the equipment door to keep the ladder from accidentally lowering while the equipment is in operation.