How to Replace Shear Pins in a PTO Snowblower

Shear pins (or shear bolts) are simple devices manufacturers incorporate into the design of all snow blower power take off (PTO) attachments in order to prevent the owner or user from severely damaging the machine by auger contact with an immovable object. Shear pins are considered routine maintenance items because over time they may weaken from vibration or simply snap in the line of duty. It is always prudent to have several sets available while conducting snow blower operations; they are easy to install in a matter of minutes and will save the machine from becoming severely damaged from unseen items in the snow.

Things You'll Need

• Socket set
• Crescent wrench set
• Light machine oil
• Clean rag
• Heavy work gloves
• Small hammer (Optional)

Instructions

1. Park the tractor on a flat hard surface, move the PTO selector to the disengaged position and set the parking brake. Shut off the engine and remove the key before attempting to perform maintenance work on the snow blower attachment.

2. Put on heavy work gloves. Clean any accumulated snow, ice or other debris from the auger blades and the auger shaft. The auger shear pin should be visible after the auger shaft is cleaned. Most PTO snow blowers have two shear pins located about 4 inches from the left and right ends of the auger shaft; the pins run through the center of the auger shaft. The auger shaft runs horizontal to the ground and typically has two auger blades attached to it.

3. Rotate the auger blades by hand slowly until one of the shear pins is directly facing you so that the pin is situated horizontal to the ground. Wipe the head of the auger shear pin down with a dry rag to remove any moisture, dirt or grease.

4. Place a socket wrench on the head of the shear pin facing you. Place a crescent wrench on the nut attached to the reverse side of the shear pin. Hold the crescent wrench firmly with one hand and turn the socket wrench counterclockwise to loosen the shear pin. Remove the nut from the reverse side of the shear pin as well any lock washers or spacers that may accompany it.

5. Press the shear pin out of the auger shaft with your fingers. If it won't budge, you may need to tap it gently from behind with a small hammer to work it free. Remember that if the shear pin is broken, it may come out of the hole pin in several smaller pieces. Try not to rotate the auger blades on the auger shaft once the shear pin has been removed since you will need the holes to remain aligned so that you can reinsert a new shear pin.

6. Apply a liberal amount of light lubricating oil onto the replacement shear pin then thread it into the shear pin hole on the auger shaft. Don't forget to put on any washers or spacers that were removed along with the old shear pin, as well as the locking nut. Get the nut finger-tight.

7. Place the socket wrench on the head of the shear pin facing you. Place the crescent wrench on the nut attached to the reverse side of the shear pin. Hold the crescent wrench firmly with one hand and turn the socket wrench clockwise to tighten the shear pin. Do not over-tighten the shear pins since they are designed to break away under inordinate amounts of stress.

8. Repeat the above procedure for each shear pin located on the auger shaft. Be sure to remove all tools, rags and other equipment before restarting the PTO attachment in order to prevent having to replace another shear pin immediately.

Tips & Warnings

• Never use any shear pins or bolts not recommended by the manufacturer of the PTO snow blower attachment since they may not be the appropriate strength rating.

References

• Snow Blower Guide: 42 Inch 2 Stage Snow Thrower Attachment (PDF)