Q 1.1.1 (8 marks)
What are the typical attributes of machinery with regard to the safety?
The typical attributes of machinery relating safety primarily concerns the machine related mechanical hazards. When it is identified that the hazards are not subject to elimination through inherently safe design, the hazards are to be reduced to an acceptable level. Or the hazards so caused are to be isolated from the operators by means of guards allowing the minimum safe distance. Two major steps are involved in the general principle of Risk management, which are 1. Risk Assessment and 2. Risk Reduction.
Risk Assessment: In general, any improvement to machine’s safety begins with a risk assessment. This operation includes a risk analysis followed by risk evaluation.
The Risk analysis has three steps,
a) Determining the limits of the machine
b) Determining the hazards,
c) Estimating the risk
After the Risk is analyzed appropriately, the Risk Evaluation process consists of making a judgement about the estimated risk level. At this step, it is determined whether the risk is tolerable or not. When the risk is considered intolerable, risk reduction measures must be selected and implemented. In order to ensure that the chosen solutions fulfill risk reduction objectives without creating new hazardous situations, the risk assessment procedure must be repeated once the solutions have been applied.
Risk Reduction: Once the Risk Assessment step has been completed, if the evaluation prescribes a reduction of risk, means to be applied to achieve the risk reduction objectives must be selected. The hierarchy in the risk reduction measures involve:
1. Hazard elimination and risk reduction,
2. Guards and Protective Devices
3. Warnings, work methods and personal protective equipment
4. Training and information
5. Validation of the final result.

Q 1.1.2 (6 marks)
Briefly describe the following terms: (a) Machinery (b) Machinery System and (c) Machinery Safety System.
(a) Machinery: The term Machinery refers to an assembly meant for a specific application, which is assembled with a drive system except for directly applied human or animal effort, typically containing linked moving parts or components.
(b) Machinery System: A machinery system is a collection of machinery arranged in a specific fashion for a certain purpose.
(c) Machinery Safety System: Machinery Safety System is a machinery system itself integrated in a certain machinery system to alleviate the hazard.

Q1.2.1 (6 marks)
Classify the machinery control systems and briefly narrate their function with reference to the operations and safety.
Machinery Control Systems can be broadly classified into two following groups with their reference to safety.
1. On/Off Control: This control System is one that activates or turns off a certain system taking the decision based on the feedback from a sensor. Often machines are equipped with sensors to identify hazards; these sensors provide feedback in the on/off controller to activate a certain machine operation if the hazard is not present.
2. Logic Control: The Logic Controllers are equipped with interconnected logic circuits or ladder circuits with multiple inputs from sensors. This control system is more safe as there are options for introducing several safety related sensors in a single control for a machine operation.

Q 1.2.2 (8 marks)
Identify the difference between these two figures with regard to the control system and briefly describe their functions.
In case of Fig 1 there is no safety related system incorporated with the control system of the machine. The operator provides the commands through the Operator Interface to the machine’s control system, which provides the control signal to the actuators to draw power and drive the machine. The sensors sense the motion, position, speed, temperatures etc. from the machine itself and provides the sensing signals to the control system of the machine. We notice there is no safety related control systems present to sense the safety of the operator.
On the other hand, in case of Fig 2, its clear that the Safety Related Electrical Control that is providing the safety function fits into the overall machine control system as a safety related part. It reads in the safety sensors via its interface modules and outputs commands via the interface to the final control elements (which remain hardwired and elctro-mechanical). The operator provides the commands through the Operator Interface to the machine’s control system, which provides the control signal to the actuators to draw power and drive the machine. The sensors sense the motion, position, speed, temperatures etc. from the machine itself

1. A 4-cylinder, 4-stroke, 1.8 liter naturally aspirated SI engine...