Active learning ideas
Open Bearing and Bushed Bearing introduce students to the world of assembly drawings. A bearing is a machine element that supports a rotating shaft and reduces friction. In this topic, students learn to draw the assembly of a simple 'block' bearing and a more complex 'bushed' bearing where a brass or bronze bush is inserted to act as a sacrificial wear surface. This requires careful alignment of multiple parts and the use of sectional views to show internal details.
Activity 01
Station 1: Identify parts of a bushed bearing (Body, Bush, Shaft). Station 2: Practice drawing the 'snug fit' of the bush. Station 3: Determine which parts should be hatched in a sectional front view.
How is the bush secured in the bearing block?
Activity 02
Students discuss: 'Why not just put the shaft directly in the cast iron block?' They explore the concept of 'sacrificial parts' and share how this saves money in industrial maintenance.
What sectioning techniques are used for bearings?
Activity 03
Students are given a 3D view of an open bearing. They must work together to decide where the cutting plane should pass to show the oil hole and the base bolts most clearly, then sketch the resulting section.
How do we align the base and the shaft hole?
A few notes on teaching this unit
Watch Out for These Misconceptions
Hatching the shaft in an assembly section drawing.
Standard convention dictates that solid shafts, bolts, and nuts are not sectioned (hatched) even if the cutting plane passes through them. Peer-review sessions using a 'Hatching Checklist' help students remember this important rule of engineering graphics.
Drawing the bush and the body as a single piece.
Students often forget the line separating the bush from the bearing body. Using two different colored pencils in initial sketches to represent different materials helps them remember to show the interface between the two parts.
Methods used in this brief
Footstep Bearing
Assembling the components of a footstep bearing used to support vertical shafts.
8 methodologies
Cotter Joint and Knuckle Joint
Drafting the assembly of socket and spigot cotter joints and knuckle joints.
8 methodologies
Flange Pipe Joint
Creating assembly drawings of standard flange pipe joints.
8 methodologies