Solution Summary: Quieter Loaders
Quieter loaders are designed to limit noise exposure from loud equipment engines by enclosing the operator.
Description:
Quieter loaders use engineering controls to limit noise exposure. Loaders use powerful diesel engines to move large amounts of earth or other materials during construction or demolition. These quieter machines are designed to reduce the amount of noise from the engine that reaches the operator. The sound level in the cabin is reduced through the use of quieter engines and specially designed cabins.
Through the use of specially designed cabin enclosures, the noise entering the loader’s cabin is mitigated and operator exposures are reduced. Sound pressure levels on the construction site, however, may still be above the OSHA permissible exposure limit and workers should wear hearing protection for more than intermittent visits.
John Deere 333D Loader
- Engine: 89 horsepower diesel
- Vehicle Weight: 11,100 pounds
- Vehicle Height: 7 feet, 1 inch
- Tipping Load: 9,425 pounds
- Bucket Capacity: 0.6 – 0.8 cubic yards
- Noise Control Methods: re-designed engine, variable-speed hydraulic drive fan, and pressurized cab isolation
- Operator Sound Pressure Level: 84 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
- Outside Sound Pressure Level: 107 dBA
Caterpillar 950K Loader
- Engine: 211 horsepower diesel
- Vehicle Weight: 42,811 pounds
- Vehicle Height: 11 feet
- Tipping Load: 26,427 pounds (with general-purpose bucket and rigid tires)
- Bucket Capacity: 2.76 – 3.79 cubic yards
- Noise Control Methods: viscous cab mounts, operator isolation
- Operator Sound Pressure Level: 71 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)
- Outside Sound Pressure Level: 110 dBA
Volvo Loaders
| Model | Diesel Engine (horsepower) | Vehicle Weight (pounds) | Vehicle Height | Tipping Load (pounds) | Bucket Capacity (cubic yards) | Operator Sound Pressure Level (dBA) | Outside Sound Pressure Level (dBA) |
| L60F | 154 | 26,020 | 10 feet 7 inches | 15,450 | 2.5 – 3.3 | 68 | 104 |
| L90F | 173 | 33,450 | 10 feet 9 inches | 20,070 | 3.0 – 3.9 | 70 | 105 |
- Noise Control Methods: viscous damper cab mountings, cab isolation
Risks Addressed:
Over time, exposure to noise levels at or above 85 decibels can lead to permanent hearing loss. The NIOSH recommended exposure limit (REL) for occupational noise is 85 decibels on an A-weighted scale as an 8-hour time weighted average (U.S. Department of Health and Human Services, 1998). OSHA limits noise exposure to 90 decibels, also on an A-weighted scale and as an 8-hour time weighted average (U.S. Department of Labor). A-weighting is an adjustment that gives lower frequencies less weight or significance than higher frequencies. An A-weighted sound level more closely resembles the human ear’s response to noise.
The American Conference of Governmental Industrial Hygienists (ACGIH) assigned noise a Threshold Limit Value (TLV) of 85 dBA as an 8-hour time weighted average. Exposure to 88 dBA is limited to 4 hour, exposure to 91 dBA is limited to 2 hours, exposure to 94 dBA is limited to 1 hour and so on. (ACGIH, 2012).
|
ACGIH TLVs for Noise |
||
|
|
Duration per Day |
Sound Level dBA |
|
Hours |
24 |
80 |
|
16 |
82 |
|
|
8 |
85 |
|
|
4 |
88 |
|
|
2 |
91 |
|
|
1 |
94 |
|
|
Minutes |
30 |
97 |
|
15 |
100 |
|
|
7.50 |
103 |
|
|
3.75 |
106 |
|
|
1.88 |
109 |
|
|
0.94 |
112 |
|
Noise exposure has also been associated with temporary hearing loss, perception of noisiness and masking, increased stress, fatigue, disturbance of sleep, decreased concentration and decreased mental performance (Osada, 1988). Noise-induced hearing loss starts in the higher frequencies (3,000 to 6,000 Hz) and slowly develops from chronic exposure to excessive sound. Sound must exert a shearing force on the hair cells lining in order to be perceived, and if the force is too strong, cell damage and cell death can occur (Berger et al., 2003).
In a study to determine time-weighted average noise exposures for heavy equipment operators, 15 noise dosimetry samples were collected for six wheel loaders. The average sample duration was 432 minutes. The time-weighted average daily noise exposure for loader operators ranged from 87 to 100 dBA with an average exposure of 94 dBA. The authors noted that noise exposure depends largely on the power of the loader’s engine (Legris, 1998).
A survey measured all of the sources of noise within a mine, including front end loaders. Most of the noise from the front end loader came from the engine and exhaust located on the rear of the machine. Measurements indicated the machine produced a sound pressure level of 72 – 84 dBA (Tripathy, 1999).
Another study measured sound levels produced by a number of machines on a construction site. The noise limit in some cities for construction equipment at 7.5 meters is about 55 dBA, but wheel loaders produce between 68 and 77 dBA at that distance. The loudest components of a loader were the engine itself and the exhaust (Ivanov, 2008).
How Risks are Reduced:
These diesel-powered machines move large amounts of earth or other materials and are designed to reduce the amount noise from the engine that reaches the operator. The controls designed to reduce noise exposure vary between machines, but include vibration-absorbing cabin mounts and variable-speed fans. Specially designed cabin enclosures for the loader operator reduce the sound level at the operator’s ear.
While there are limited peer-reviewed data on these specific controls, manufacturers’ testing indicates exposure to noise can be significantly reduced through the use of noise control techniques. The extent of the reduction is dependent on the type of work being performed, the size of the engine, the amount of noise in the environment, the machine, the level of effort required by the machine, and the operator’s proximity to the engine.
Industrial hygienists use sound level meters or noise dosimeters to determine noise levels and recommend the use of quieter techniques to prevent hearing loss and reduce the risk of accidents. Proper maintenance and retrofitting of existing equipment can decrease excess sound as well (Suter, 2002).
A review of construction equipment was conducted to determine possible solutions for noise emitted by the machines. The exterior noise of the loader may be reduced by 10 dBA if certain measures were taken. First, a re-designed exhaust muffler would need to be fitted to the machine, along with acoustical baffles or a sound proof enclosure for the hydraulic system. To further ensure that the goal is met, an enclosure for the bottom portion of the engine should be constructed as the engine is the loudest component of the loader. With all the upgrades in place, the loader should be close to meeting noise standards in most cities (Ivanov, 2008).
John Deere claims that its pressurized cab reduces sound levels by 50%.
Volvo states that the L60F loader’s operator sound pressure level is 68 dBA.
Effects on Productivity:
Lower noise levels are expected to reduce stress and fatigue, and increase the concentration and mental performance of workers. Improved worker health, comfort and concentration may lead to greater productivity. Reduced sound levels can also lower the risk of accidents as communication among workers is easier and more effective.
Additional Considerations:
The use of diesel-powered equipment poses the risk of carbon monoxide exposure, especially in areas where airflow is reduced. Steps to control exposure are important because the gas is invisible, odorless and tasteless. Poisoning by carbon monoxide can occur quickly indoors, but working outdoors does not ensure operators won’t be overcome. Small, inexpensive personal monitors should be worn by the operator to warn of unacceptable exposures. Equipment should not be left idling to cut down on carbon monoxide and to conserve fuel.
As is the case with any construction equipment, users should follow manufacturer safety recommendations and comply with any applicable local, state or federal regulations.
Contributors:
Andrew Kingston, Michael R. Cooper and Bruce Lippy - The Lippy Group, LLC
Availability
NIOSH Workplace Solutions Sheet
The National Institute of Safety and Health (NIOSH) has published a series of “Workplace Solutions”, which are easy-to-understand recommendations from NIOSH research results. Related to this Construction Solution, please find more information on:
Preventing Injuries When Working with Hydraulic Excavators and Backhoe Loaders
Caterpillar 950K Loader
To obtain information, visit http://www.cat.com/en_US.html
or contact 1-309-675-1000
John Deere 333D Loader
To obtain information, visit http://www.deere.com
Volvo L60F L90F Loaders
To obtain information, visit http://www.volvoce.com/constructionequipment
or contact 1-828-650-2000
