Amazon Maintenance Technician Sample Test

The correct answer is D.

A double-pole, double-throw (DPDT) relay, and its schematic is shown in the figure below. It contains six terminals labeled 1 through 6. The middle pin is the output port, and the side pins are connected to the circuits. The output is selected from the two circuits with the help of the manual switch on top of the relay. The simplest way to control two circuits is to use DPDT as shown in the figure below.

Therefore, D is the correct choice. Choice A cannot be correct because it can control only one circuit. Choice B provides two outputs rather than two inputs. In addition, if we use two DPST relays, it can provide the same result. However, it is mentioned to use a single relay. Therefore, C cannot be correct as well.

The correct answer is D.

Intermittent welding is a joint welding technique where the fillet weld is done non-continuously. Apart from the fact that it’s more economical (since less energy and materials are used), it is also easier to repair). Since the welding is not continuous, in a case of failure, only a small part of the welding is broken before the strain is released, thus making it easier to repair. Had the welding been continuous, the entire joint would have been torn apart, requiring the re-welding of the entire joint.

Naturally, intermittent welding is not as strong as full welding.

The correct answer is A.

The difference between the three flames is rooted in the acetylene-oxygen ratio in the flame. A neutral flame has the exact ratio required for combustion. The neutral flame is solely a heating device, and does not react with the welded metal.

The carburizing flame has excess acetylene, which causes the welded metal to absorb carbon.

The oxidizing flame has excess oxygen, which causes the welded metal to oxidize. Due to its oxidizing effect, it is used mainly for non-ferrous metals such as bronze and copper.

The correct answer is C.

In the splash lubricating system, oil is mechanically splashed upwards from pans or trays in the crankcase, creating a mist that lubricates the internal parts of the mechanism. The splash method is an unreliable method since the oil level in the crankcase will have a substantial influence on the lubrication level. A high oil level may cause excess lubrication, whereas an oil level that is too low will cause inadequate lubrication. For that reason, splash method lubrication is only used in very small engines such as a lawnmower.

The correct answer is D.

The three components: Filter, Regulator and Lubricator (known also as the FRL unit) are designed to treat the air leaving the compressor before entering the system.

The filter strains the air of small particles and contaminations, the regulator supplies air at a determined, constant pressure, and the lubricator creates a mixture of air and oil mist to lubricate the system’s parts, thus improving their functioning and extending their service life.

The filter must be installed before the regulator, which, in turn, must be installed before the lubricator (so that the contaminating particles or lubricant oil particles do not interfere with the regulator’s action) . The filter is also installed before the lubricator so that the oil particles are not filtered from the air.

The correct answer is B.

When activated by AC current, the current changes direction as many as 60 times per second when alternating between positive and negative peaks. As such, there are 60 times per second when the current drops to zero, and as a result (since the solenoid's magnetic field is proportional to the current), so does the magnetic field inside the solenoid. That causes the return spring to overcome the solenoid's actuating force for a very brief moment, many times per second. This action results in a constant vibration of the armature causing a humming sound as well as extra stress on the solenoid's components.
This problem can be solved by a shading ring. The ring, a small conductive ring usually made of copper, generates a magnetic field in a 90 degrees phase difference to that created by the solenoid itself, thus keeping the armature in place when the current periodically drops to zero.