Farm Machinery and Equipment-II 3(2+1)

LESSON 30. SAFETY REQUIREMENT IN AGRICULTURAL MACHINES

WHOSE CONCERN IS SAFETY?

Safety is an aspect, which is covered under the discipline of Ergonomics and it is the concern of the farm machinery designer, manufacturer, distributor, user, government, public and national standards organization of a country. Each of these agencies can play an important role in minimizing the number of accidents and promoting safety consciousness. For instance, the designer can provide different safety devices, such as guards, shields, safe distances and fail-safe mechanisms. A manufacturer similarly, can ensure adherence to the available standards and use safe and sound materials of construction. Likewise, the distributor and the user can promote farm machinery safety by ensuring that they propagate and use only such machines which are equipped with proper safety provisions. The standards organization of a country has an important role to play by formulating relevant safety standards, codes and test procedures. The Government has to play an important role by making it mandatory to adopt available safety standards by all concerned to minimize the number of accidents.

COMMON CAUSES OF MACHINERY ACCIDENTS: Following are the basic causes of farm machinery accidents:

a) Design errors

b) Failure to install adequate safety devices

c) Employment of safety devices, which failed in use (Brake failure)

d) Failure to make a safety-check after manufacture

e) Use of unsafe/unsuitable material in construction

f) Use of inferior/improper manufacturing processes, which led to defective parts

g) Failure to plan for such uses which were unintended by the manufacturer

h) Improper maintenance & failure to foresee consequences of ordinary wear and tear.

i) Failure to stick to proper standards

j) Addition of undesired/un-required part to the product

k) Failure to warn of the dangers arising from the defective design.

TYPES OF AGRICULTURAL MACHINERY ACCIDENTS: Following are the common types and causes of farm machinery accidents:

Overturns: Machines working at steeper slopes or at higher speeds, quick turning and quick starting.

Run-over: Person inspecting the machine or certain components without turning off the engine.

Trap: Person wearing loose clothes gets wrapped in moving belts, chains, shafts etc.

Cut: Body parts touching the cutting knives, blades, sharp edges etc.

Crush: Person sitting or standing between the machine and its attachment or machine and wall or carrying out under attachments in the tractor or machine.

Fall: Person slipping from the machine platform or steps.

Burn: Body part touching the exhaust manifold pipe or opening the radiator cap when the engine is hot.

Fire: Careless use of fire, smoking, exhaust emissions, carbon particles etc.

Health hazard: Noise, vibration, chemical spray etc.

Hits: Thrown objects.

TECHNICAL REQUIREMENTS FOR ENSURING MACHINERY SAFETY

a) Safety guards: These are protective devices designed and fitted to a machine to minimize the possibility of machinery hazards as well as to restrict access to hazardous area.

b) Safe distances: These are a means to provide the guard where the possibility of contact with the hazard is minimized by the combination of the guard configuration and proper size of openings, if any.

c) Safety devices: A safety device is provided to minimize the incidence of machinery hazards like unintended movement. Therefore, safety-starting device, emergency stopping switch and similar other safety provisions are provided to eliminate the accidents.

d) Safety signs and warnings: This includes the information affixed on equipment to alert/warn the operator and others working in its surroundings against hazards, which can cause body injury. The sign/caution/warning plate should be permanently fitted/attached to the machine such that it is readily visible and cannot be easily removed.

e) Operational ease and comfort: The operating controls need to be designed and installed in such a way that these could be operated with ease and safely from the operator's seat or work place. Maximum actuating force values required to operate various controls are shown in Table 1.

TESTING OF AGRICULTURAL MACHINERY FOR SAFETY

The main objective of safety testing is to ensure the safety of all those who work on the machine and to prevent human accidents. All technical safety requirements as specified in relevant standards need to be checked and verified thoroughly and reported in the test report. Given in Table 2 is a list of some of the available safety standards and codes formulated by different agencies and organizations.

Table 1: Maximum actuating force required for operating controls as per ISO recommendations.

 

Controls	Type of control	Maximum actuating force to operate control (N)	Type
Service brake1	Pedal operated	600	Pressure
	Hand lever	400	Traction
Parking brake	Pedal operated	600	Pressure
	Hand lever	400	Traction
Single clutch	Pedal	350	Pressure
Duel clutch	Pedal	400	Pressure
PTO coupling	Pedal	300	Pressure
	Hand lever	200	Traction
Manual steering system2	Steering wheel	250	-
Power-assisted steering system with failure of power assisted steering force	Steering wheel	600	-
Hydraulic power lift system	Hand lever	70	Pressure & traction

1. It should be possible to achieve effective braking performance when these forces  are applied.

 2. Force required to achieve a turning circle of 12 m radius.

 

Table 2: Selected safety standards and test codes formulated by different agencies.

1) OECD Standard Code for the Official Testing of Safety Cabs and Frames Mounted on Agricultural Tractors, OECD Directorate for Agriculture and Food, 2, rue Andre-Pascal, 75775 Paris Cedex 16, Paris, 1974, France.

2) Occupational Safety and Health Standards for Agriculture, Part 1928, Applicable Standards from 29 CFR 1910, US Department of Labour, USA.

3) BIS 11442-1985: Operator's Field of Vision, Method of Test, Bureau of Indian Standards, New Delhi, India.

4) BIS 11821-1986: Protective Structures, Method of Test, Bureau of Indian Standards, New Delhi, India.

5) BIS 12061-1987: Braking Performance Test, Bureau of Indian Standards, New Delhi, India.

6) BIS 12180-1987: Noise Measurement, Method for. Bureau of Indian Standards, New Delhi, India.

7) BIS 9019-1979: Safety requirements for power threshers, Bureau of Indian Standards, New Delhi, India.

8) BIS 9020-1979: Safety requirements for power threshers, Bureau of Indian Standards, New Delhi, India.

9) BIS 9129-1979: Technical requirements for safe feeding systems for power threshers, Bureau of Indian Standards, New Delhi, India.

10) BIS 10740-1983: Operating Requirement for PTO Driven Implements, Recommendations for, Bureau of Indian Standards, New Delhi, India.

11) BIS 12239-1988: Safety and Comfort of Operator, Guide. Bureau of Indian Standards, New Delhi, India.

12) ASAE Standard (S350): Safety-alert symbol for Agricultural Equipment, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

13) ASAE Standard (S365T): Brake Test Procedures and Brake Performance Criteria for Agricultural Equipment, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

14) ASAE Standard (S338): Safety Chain for Towed Equipment, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

15) ASAE Standard (S318.6): Safety for Agricultural Equipment, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

16) ASAE Standard (S355.1): Safety of Agriculture Loaders, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

17) ASAE Standard (354.1): Safety for Farmstead Equipment, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

18) ASAE Standard (S351): (Safety) Hand Signals for use in Agriculture, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

19) ASAE Standard (S335.2): (Safety) Operator Controls on Agricultural Equipment, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

20) ASAE Standard (EP371): (Safety) Preparing Granular Application Calibration Procedures, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

21) ASAE Standard (S383): (Safety) Roll-Over Protective Structures (ROPS) For Wheeled Agricultural Tractors, American Society of Agric. Engineers, St. Joseph, Michigan, USA.

22)  ASAE Standard (S276.3): (Safety) Slow-Moving Vehicle Identification Emblem, American Society of Agricultural Engineers, St. Joseph, Michigan, USA

 METHODS OF SAFETY TESTING

a) General principles for guarding

i) Conform to relevant legal/standard organization requirements.

ii) Be considered a permanent part of the machine.

iii) Afford maximum positive protection

iv) Prevent access to danger zone during operation

v) Not weaken the machine

vi) Should not interfere with the efficient operation of the machine

vii) Should not cause discomfort to the operator

viii) Be designed for specific job/machine with provisions for proper adjustment, maintenance and repairs

ix) Be durable

x) Be constructed strongly enough to resist normal wear and withstand long use with minimum maintenance. It should not itself be a source of hazard.

xi) If possible it should be interlocked with the machine so that the mechanism can not be operated unless the guard is in place.

b) Parts to be inspected for proper guards/shields

(i) All shafts including joints, shaft ends, crankshafts, universal joints, keys, pins, set screws etc. that protrude from moving parts.

(ii) Pulleys, flywheels, gears, chains, sprockets, belts, clutches, couplings, cables etc.

(iii) Working parts of machines such as rotary tines, cutting blades of stubble shavers and mowers, cutter-bars, knotter mechanism of binder and baler, digging blades, conveyers, oscillating linkages, sieves etc.

(iv) Ground wheels, tyres, and tracks of crawler type tractors adjacent to the operator seat.

In all machines received by a Testing Centre, the above components need to be carefully inspected and observations regarding the provision of guards/shields ought to be included in the test report.

c) Strength of guards: The guards should be sufficiently strong. The test engineer may refer to the following standard while testing the guard:

1928.57 -Guarding of farm field equipment, farmstead equipment and cotton gins-Occupational safety and health standards for agriculture, US Department of Labour, USA

According to this standard, the guards need to be provided and located to protect against inadvertent contact with the hazardous components being guarded. Unless otherwise specified, each guard and support shall be capable of standing the force that a 114 kg individual, leaning on or falling against the guard could exert upon the guard. The guards shall be free from burrs, sharp edges and sharp corners and shall be securely fastened to the machine.

d) Guards for PTO-Shaft: The PTO-shaft shall be guarded by a casing cap, which shall be firmly screwed and bolted to the machine body. A casing throughout its length shall guard the PTO-shaft as well as the universal joints. The casing shall be secured firmly and held in stationary position.

e) Requirements for safety devices

The following points shall be carefully checked in respect of the safety devices provided in different types of farm machines during the course of testing of such equipment:

(i) Each stationary machine shall have the provision to disengage the power drive shaft. The control of the device shall be located within easy reach of the operator.

(ii) Machines such as a stubble shaver and brush cutter shall be provided with adequate means of disengaging the power to the cutting knives easily and promptly.

(iii) A portable type power unit such as the power knapsack sprayer shall be provided with a quick release clutch to enable the operator to disengage the power.

(iv) Power driven machines shall be equipped with a provision to stop the prime mover instantly.

(v) All machines with lifting members shall be provided with a locking device to keep the member in raised position and prevent accidents due to fall.

(vi) The combine shall be equipped with a device to disengage the power to the knife-bar automatically in the event of clogging.

f) Braking devices: The following points shall be checked in respect of the braking devices for testing from the safety point of view:

a) The towed equipment such as trolleys shall be provided with the parking brakes.

b) Self-propelled machines shall be provided with both the service brakes and the parking brakes.

g) Requirements for operator's work place: The following points shall be checked in respect of the operator's work place while testing a machine for safety:

a) All machines requiring the presence of an operator/worker shall be provided with handles/hand-holds to ensure the safety and convenience during mounting and dismounting.

b) All machines requiring an operator/worker to sit on the machine shall be provided with a comfortable seat with adequate footrest. The seat shall be adjustable and it shall adequately support the operator/worker in all working and operating modes and shall prevent the operator from slipping off the seat.

c) The platform on which the operator/worker is required to stand during operation shall be levelled and have a non-slippery surface. It shall be provided with guards/rails around it.

h) Requirements for operating controls: The operating controls such as steering wheel or lever, gear selection lever/brake, clutch and switch shall be arranged and fitted in such a way as to allow the safe and easy control by an operator while standing or sitting in the normal operating position. The function and the operating method of these contr01s shall be marked clearly.

TESTING OF ROLL OVER PROTECTIVE STRUCTURES (ROPS): ROPS are now a mandatory requirement for all agricultural wheel tractors in all developed countries for the protection of the operator in the event of accidental overturning. The ROPS are tested in accordance with the following standards/test codes:

1) 1.0ECD Standard Code for the Official Testing of Safety Cabs and Frames Mounted on Agricultural Tractors, Directorate for Agriculture and Food Organization for Economic Cooperation and Development, Paris, France'-1974.

2) Part 1928, Sub part C- Roll Over Protective Structures-Test Procedures and Performance Requirements. Applicable Standards from 29 CFR 1910, Occupational Safety and Health Standards for Agriculture, OSHA, US Department of Labour, USA.

GUARDS FOR HOT PARTS AND FIRE PROTECTION: For testing of the engine/prime mover/equipment with hot parts, the following observations shall be recorded:

i) Any hot part, which may cause burns to the operator or any other person working on the machine shall be fitted with proper guards.

ii) Hot parts such as exhaust pipe shall be designed and fitted in such a way that these do not pose any hazard to the operator.

iii) Spark arrester shall be provided with the exhaust silencer to arrest the glowing carbon particles.

PROTECTION AGAINST THROWN OBJECTS: While testing a machine, it shall be ensured that there are no working parts of the machine, which may produce lead to throwing of such objects, as stones, fragments of the crop or cutting knives. All such parts shall be guarded adequately to ensure the safety of the operator.

PROVISION OF SAFETY SIGNS: While testing a machine, it shall be ensured that the safety signs have been provided adjacent to the following parts:

(i) Dangerous parts which are difficult to protect by safety guards.

(ii) All hazardous parts, which need alerting the operator against hazards.

MEASUREMENT OF NOISE LEVELS: During testing, the noise levels produced by a prime-mover/ machine shall be measured by a sound level meter at the operator's ear level. Exposing the ear to excessive noise results in shifting of the hearing threshold levels of the operator upward. Frequent exposure leads to permanent threshold shift and eventually to the hearing loss. The permissible noise levels and the effects of vibrations on humans are shown in the Table 3.

 Table 3: Permissible sound levels for occupational safety of ears.

Duration/day (h)	Sound level dB(A)
8	90
6	92
4	95
3	97
2	100
1.5	102
1	105
0.5	110
0.25 or less	115

POSITIVE PRINCIPLES FOR SAFE USE OF FARM EQUIPMENT: Following points need to be kept in view to avoid the accidents while operating a farm machine:

(i) Proper environment, which should reduce fatigue and stress

(ii) Proper placement of controls and instruments to ensure easy accessibility.

(iii) Proper identification of controls & instruments

(iv) Isolation of operator and any other person coming into contact with the machine from dangerous mechanisms, e.g. cutters, rollers thrashing cylinders etc.

(v) Provide adequate guarding where persons are likely to approach within reach of dangerous mechanisms.

(vi) Guard against falls with adequate rails, etc.

(vii) Provide clear and easy path to the operating position.

(viii) Design mechanisms and controls to "failsafe", i.e. to revert to safest state in case of mechanical/operational failure.

(ix) Provide "Overload" and similar devices to avoid critical operating state.

(x) Ensure adequate operator visibility of possible hazardous situations.

(xi) Proper latches/devices to ensure that the equipment is not ~ set in operation by accident (eg. chaff cutters) 

(xii) Provide interlocks to minimize unsafe operation.

(xiii) Provide easily reached and operated "emergency-stop" facilities.

(xiv) Avoid heavy lifting/carrying of equipment.

(xv) Provide adequate supports so that hazards due to the equipment overturning are minimized.

(xvi) Prepare clear and unambiguous operating instructions.

(xvii) Design lubrication and other maintenance facilities so that the work can be easily accomplished.

(xviii) Provide labels laying down clear instructions on methods of carrying out maintenance and routine repairs & overhauls.

(xix) Design components for easy & safe removal.

(xx) Provide proper earthing and guarding for all electrical circuits.

(xxi) Where a hazard is unavoidable, provide warning signboards to ensure that operators and others recognize the danger.

(xxii) Insist on regular inspection and maintenance.