December Alert

 

How fast are you? Are you fast enough to avoid an injury? Let’s find out! Before you proceed with this Safety Alert, there is one test you should take; A reaction test. You will need a yard stick, table, chair, and one or more volunteers.

  1. Ask your first volunteer to sit in the chair with good upright posture and eyes looking across the room.  
  2. Have the volunteer place their forearm (the part of the arm from elbow to hand) so it extends over the edge of the table.
  3. Ask the volunteer to place their thumb and index (pointer) finger on either side of the bottom of the vertically placed yardstick. The number “1” should be on the bottom, the “36” near the top. 
  4. Let your volunteer practice holding the ruler with those two fingers.
  5. Now, ask your volunteer to remove their fingers from the ruler while you continue hold it so that the bottom of the ruler is at a height of 1 inch above their fingers.
  6. Tell your volunteer that you will release the ruler without telling them. Their job will be to catch it with their thumb and forefinger as soon as they sense it dropping.  
  7. Drop the ruler. When your volunteer catches it, record the number on the ruler displayed just over their thumb. The lower the number, the faster their reaction time.
  8. Conduct several trials with the same volunteer, dropping the ruler from 1 inch above their fingers each time.
  9. Use the chart below to convert the distance to time.

 

Distance in Inches

 

Reaction Time in Seconds

 

Distance in Inches

 

Reaction Time in Seconds

1

          0.0721687836

11

          0.23935677694

2

          0.10206207262

12

          0.25

3

          0.125

13

          0.26020824993

4

          0.1443375673

14

          0.27003086243

5

          0.16137430609

15

          0.27950849719

6

          0.1767766953

16

          0.28867513459

7

          0.19094065396

   17   

          0.29755951786

8

          0.20412414523

18

          0.30618621785

9

          0.21650635095

19

          0.3145764348

10

          0.22821773229

20

          0.32274861218

 

 

 

 

 

 

 

 

Tractors are a vital machine for many agribusinesses. One of the most important parts of thetractor is the power take-off or PTO. Since the 1930’s PTOs have revolutionized the agricultural world. It is one of the oldest and most persistent hazards associated with farm equipment. The PTO allows the power to be transferred from the tractor to a PTO-driven machine or implement. The power is transferred by connecting a drive shaft from the machine or implement to the PTO stub on the back of the tractor. The PTO and drive shaft then rotate at 540 rpm (9 revolutions/second) or 1,000 rpm (16.6 revolutions/second) when operating at full recommended speed. At those speeds, it is easy to see how PTOs can be dangerous.

Entanglement is the leading cause of injuries related to PTO hazards. Below are real world examples of how serious these hazards can be.

  • A 24-year-old male farmer died after becoming entangled in the unguarded rotating driveline shaft of a manure spreader. The spreader was connected to a tractor equipped with a PTO, which powered the spreader driveline. The victim was working alone in the barnyard, replacing a bolt on the shaft. He apparently had completed this task and was standing on ice-covered soil near the rotating driveline. Then, he either slipped and fell onto the driveline or the rotating shaft caught his clothing. The PTO spun him around the driveshaft, where portions of his clothing were entangled and torn from his body. His wife approached the site of the incident, when her husband had not returned to the farmhouse as expected, and found him entangled on the driveline. The tractor engine was not running. Emergency services pronounced the farmer dead at the scene.
  • A 17-year-old male farm worker died when he became trapped in a hay baler that caught fire. The farm worker was working alone baling dried wheat straw for hay. Evidence suggests that the round hay baler became jammed, and the clutch temporarily shut down the PTO. The worker apparently climbed on top of the baler to clear the jammed wheat straw by using his feet. The jam cleared, and the clutch put the PTO back into motion. The baler rollers suddenly started moving and trapped the worker’s leg inside the baler. The rollers and belts spinning around the hay started a fire. The worker died at the scene from smoke inhalation and burns.
  • A teenage female was helping her family load corn into a grain elevator when her jacket sleeve became entangled by the elevator PTO shaft. Once caught, her body was flung around the shaft until her arm was torn from the socket before the tractor could be shut off.
  • A small child was killed when as an extra rider on his father’s tractor; he slipped off and became entangled by a spinning PTO shaft. His father grabbed for the boy as he began to slip but was unable to keep him out of the shaft.

Purdue University has a comprehensive study of power take-off injuries. They found PTO entanglements generally:

  • involve the tractor or machinery operator 78 percent of the time.
  • shielding was absent or damaged in 70 percent of the cases.
  • entanglement areas were at the PTO coupling, either at the tractor or implement connection just over 70 percent of the time.
  • a bare shaft, spring loaded push pin or through bolt was the type of driveline component at the point of contact in nearly 63 percent of the cases.
  • stationary equipment, such as augers, elevators, post-hole diggers, and grain mixers were involved in 50 percent of the cases.
  • semi-stationary equipment, such as self-unloading forage wagons and feed wagons, were involved in 28 percent of the cases.
  • nearly all incidents involving moving machinery, such as hay balers, manure spreaders, rotary mowers, etc., were non-moving at the time of the incident (the PTO was left engaged).
  • only four percent of the incidents involved no attached equipment. This means that the tractor PTO stub was the point of contact four percent of the time.

A PTO shaft is roughly 2 inches in diameter, giving it a circumference of 6.28 inches. If you are using a 540 rpm shaft, it will make 9 revolutions per second. That means, every second the PTO can entangle 56.52 inches of material. So, how fast are you? Use the following chart and your reaction time to determine how many revolutions the PTO will make before you can react.

Reaction Time in Seconds

PTO @ 540 RPM (rotations)

Corn Snapper Rolls

Tractor @ 20 MPH

(Dist. in Ft.)

PTO @ 1000 RPM (rotations)

 

Object Thrown by Lawn Mower

(dist. in ft.)

 

.1

 

.9

1.2

2.93

1.67

25

 

.2

 

1.8

2.4

5.86

3.34

50

 

.3

 

2.7

3.6

8.79

5

75

 

.4

 

3.6

4.8

11.72

6.68

100

 

.5

 

4.5

6

14.66

8.35

125

 

Murphy, Dennis. “Power Take-Off (PTO) Safety.” NASD, nasdonline.org/905/d000745/power-take-off-pto-safety.html.