Lifting Bridge.

Posted on April  14th, 2009 by Technology Department 

First of all, have a look at "Los puentes mas bonitos ", in Spanish.


lifting bridge


Note: Once finished, models shouldn't be used as toys in the commercial sense of the word. They are an educational tool, suitable for the classroom


1.) Technical Information

 Activities to be undertaken

  •  Interpretation of diagrams and plans
  •  Construction of various structures
  •  The construction and adjustment of a reduction motor
  •  Assembly of the electronics involved
  •  Mechanical assembly  
  • Required tools (not included in the kit)

  •  Set square
  •  Saw
  •  Files
  •  Vertical drill and drill bits of 3 and 4mm
  •  Screwdriver
  •  M3 and M4 keys
  •  Scissors
  •  Pliers
  •  Soldering iron and solder
  •  White glue and glue gun
  •  1.5V batteries
  • 1.3 Measurements


    1.4 Objective

    The construction of the bridge will allow the students to learn how to resolve two problems-How to ensure the safe passage of people and vehicles over the bridge-How to equip the bridge to allow the passage of boats taller than the bridge 

    2.1. Material provided

    Material Number Measurements   Piece Picture


    1 10x140x498 mm Base lifting bridge material 1
    2 Pine strip 1 10x50x300 2x10x50x100


    3 Pine strip 4 10x75x80  
    4 Pine strip 1 10x50x350  
    5 Plywood 1 5x70x250 1x5x70x60



    6 Pine strip 4 10x15x325 1x10x15x310






    7 Wooden Pulley 2 Ø10x10 mm  
    8 Pine strip 3 5x10x250 1x5x10x115






    9 Rods 12 Ø3x500 mm  
    10 Cotton thread 1 2 meters  
    11 Metal rod 1 Ø3x95 mm  
    12 Retention rings 6 Ø3  
    13 Metal rods 2 Ø3 x 70 mm  
    14 Mounting blocks 2 30x53 mm  
    15 PVC fittings 2 Ø7 x 25 mm Reducing motor
    16 Brass fitting 1 Ø4 x 25 mm Reducing motor
    17 Motor 1 Ø21 x 25 mm  
    18 Double toothed wheel 4 50/10 teeth 3 whites, 1 red


    2.2 Material provided

    Material Number Measurements Picture
    19 Pinion 1 10 teeth lifting bridge materials 2
    20  strips connections 2 12 connections
    21 LED 2 Ø 5mm red
    22 LED 2 Ø 5 mm green
    23 Resistors 2 130 Ω
    24 Limit switches 2 250 V/5A
    25 Sliding switch 1 6 contacts
    27 Electric wire 1 10 m
    28  screw bolt 2 M4 x 30 mm
    29 Nut 4 M4
    30 Washer 6 M6
    31 screw bolt 2 M3 x 35 mm
    32 screw bolt 1 M3 x 20 mm
    33 Nuts 4 M3
    34 Washer 8 M3
    35 eyebolt 4 Ø 3 x 10 mm
    36 Screws 6 DIN 7981
    37 Screw 8 DIN 96
    38 Screw 2 DIN 7981
    39 Battery holder 1 2 (1,5 V) battery
    40 Battery holder connector 1  


    3. Construction

    Before starting to make the bridge it is important to familiarise yourself with the general plans of the bridge (figures 27/28) and the diagram of the electrical layout.  

    Construction phases

    3.1. The construction of the moving section of the bridge 3.2 The construction of the bridge pillars3.3 The construction of the barrier3.4 The construction of the reduction motor3.5 The assembly of the different components3.6 Electrical installation 

    3.1 The construction of the the moving section of the bridge

    3.1.1 Cut two 80 x 50 x 10 mm pieces and two 50 x 50 x 10 mm pieces of wood from the piece of wood measuring 300 x 50 x 10 mm (2), using a saw. The two pieces 80 x 50 x 10 mm are going to be used for the bridge pillars


    image 5 3.1.2 Mark the centre of the two 50 x 50 x10 mm pieces, obtained in point 3.1.1, and round them off as shown in figure 2. These pieces will serve as the base for the moving section of the bridge.

    3.1.3 Drill a hole through the two pieces at the same, using a Ø3mm drill piece, at the point indicated in figure 2.

    Note: Put the pieces on on top of the other, fix them together with adhesive tape and drill both holes at the same time. The Ø 3 x 95 mm shaft (11) will be passed through this hole later. 3.1.4 Make a 2.5mm wide and 55mm long groove in both sides of the 10 x 50 x 350 mm strip of wood (4), as shown in figure 3. figure 3

    figure 3 3.1.5 Glue the two perforated 50 x 50 x10 mm pieces onto the walkway piece of the bridge (4), as shown in figure 3. 3.1.6 Cut the following pieces, indicated in figure 4, from the two large pieces (8) of 500 x 10 x 5 mm. 1 piece of 115 x 10 x 5 mm 1 piece of 90 x 10 x 5 mm 3 pieces of 80 x 10 x 5 mm 1 piece of 70 x 10 x 5 mm 3 pieces of 15 x 10 x 5 mm figure 4 3.1.7 Make a slit, 1mm wide and 5mm long, in both ends of the 115 x 10 x 5 mm piece of wood (obtained in point 3.1.6), as shown in figure 5.

    figure 5

    3.1.8 Make a piece like the one shown in figure 6 from one of the 15 x 10 x 5 mm pieces (obtained in point 3.1.6). Then glue this piece to the end of a 80 x10 x 5 mm piece of wood (from point 3.1.6) in the position indicated in figure 6. figure 6

    3.1.9 Stick the 115 x 10 x 5 mm piece from point 3.1.7, with the the piece of 80 x 10 x 5 mm, obtained in point 3.1.8, and the 80 x 10 x 5 mm strips onto the walkway of the bridge, as shown in figure 7. Fix an M4 washer (30) to the outside face, over the hole, as shown in figure 7. figure 7 3.1.10 Make the frame and rails of the walkway of the bridge using the rods (9) and the template in figure 29, on the scale 1:1. Make one side first, then the other and glue them to the underside of the walkway. Then fix the crossbeams (a) between both frames and the diagonals (b) to each end triangulating the end of the structures, as shown in figure 8.

    3.1.11 Make the two rails by cutting eleven short pieces and one long piece for each side from the rod (9). Space the short rods equally, as shown in figure 8. Stick the whole together and glue to the bridge. Note: Assure yourself that neither the frame nor the rails exceed the limits defined in figure 8 as this could cause problems with the raising and lowering of the bridge.

    3.2 The construction of the bridge supports

    3.2.1 With care, cut out a hole in one of the 80 x 75 x 10 mm pieces with a coping saw, as shown in figure 9. This is where the sliding switch will be placed later, to connect and disconnect the current. Take a second 80 x 75 x10 mm piece and bevel the corners of both pieces at the angle shown and make a hole in the same position in both with a 3mm drill, as shown in figure 9.

    Note: Put the two pieces one on top of the other, join them together with adhesive tape and do the beveling and perforating in both at the same time.

    image 9

    3.2.2 Stick the two large 80 x 75 x 10 mm pieces with the Ø3mm hole to one of the 75 x 50 x 10 mm pieces obtained in point 3.1.1, as shown in figure 10. Do the same with the two 80 x 75 x 10 mm pieces without holes and another 75 x 50 x 10 mm piece.

    figure 10

    3.2.3 Stick the first piece (the one with holes), obtained in point 3.2.2, to the large 495 x 140 x 10 mm (1) piece, to act as a bridge support, as shown in figure 11. figure 11 3.2.4 Place the moving part of the bridge (from point 3.1) between the two bridge supports and fix them in place using the Ø 3 x 95mm metal shaft (11). Make sure it can move. On the right, the board must be a little lower than the horizontal. If necessary, file the support down a little at the points where it supports the walkway of the bridge. See figure 12. Fix the rod in place with the washer (12). See figure 12 Attach the second support (without holes) to the end of the base. Make sure there is a gap of 0.5 and 1 mm between the support and the walkway. figure 12  


    pillars:  vertical support; a column

    More information 

    Posted on 2009