Term 'lobes' is related to following engine components:

Question

Question

This question was previously asked in

RRB ALP Mechanic Diesel 21 Jan 2019 Official Paper (Shift 1)

Answer 1

Explanation:

Camshaft:

The camshaft is used to convert the rotary motion into a reciprocating motion with the help of the cam lobe.
This reciprocating motion is transmitted to the valve through the tappet, push-rod, and rocker levers.
The camshaft is driven by a crankshaft and it rotates at half the speed crankshaft.
The camshaft also drives the oil pump shaft.
In petrol engines, the fuel pump and the distributor get their drive from the camshaft.

Construction of the camshaft:

The camshaft (2) is either forged or cast with the cam lobes (1) one for each valve.
The camshaft has a series of support bearings along its length.
The cam surface is hardened for longer life.
In some engines, the axis of the tappet/lifter (3) is slightly offset from the axis of the cam lobe (1).
This offset gives a little rotation to the tappet/lifter when it moves up.
So the bottom of the tappet/lifter (3) wears out uniformly.
The lifter/tappet (3) rests on the cam lobe (1).
The lifter (3) remains in its position on the base circle (4).
When the cam rotates the lobe lifts the lifter (3).

F3 Vilas Engineering 9.1.2023 D2