A loaded logging truck was traveling at 90km/hr down the highway when a switch on the dash was accidentally hit, which caused the release of the pin on the trailer hitch. This caused the loaded trailer to become separated from the truck and cross the center line of the highway. The load of logs came to rest against a guard rail on the opposite side of the highway.
The trailer configuration was a quad-axle short logger, similar to what is pictured below.
No one was injured in this incident but there was potential for a very serious collision.
These types of trailers have a telescopic reach with an airlock system. In this incident, the reach separated from the truck when the switch has activated. The trailer reach inner tube should not have been able to detach from the outer tube and release the trailer due to a shim mechanism. If these shims are excessively worn down, this allows the inner reach to separate from the outer reach.
Review the following recommendations for practices that can prevent these types of incidents from occurring.
Secure Items in Cab
- Loose items in the cab may accidentally fall or shift and activate controls. Items like radio mics, lunch and tools should be secured so they will not shift around.
- Managing loose items while driving can be a distraction and cause the driver’s focus to shift from the task at hand.
Inspections and Preventive Maintenance
- A comprehensive inspection and maintenance program should include the inspection of all the trailer components especially the reach and hitch safety features that connect the truck and trailer.
- The following is an excerpt from the service manual for these types of trailers: Special attention must be given to maintenance, lubrication, inspection and wear of these reaches. Always inspect the reach after operating the index pin to ensure it has ‘latched/indexed’ down into the desired position. DO NOT open air latch/index mechanism when vehicle is in motion. Ensure the air friction clamp is adjusted properly to keep the slack from reach tubes. Inspect the reach shims/stops for wear and replace as necessary. These shims/stops are what prevents the reach from coming apart when the latch/index pin is open. Inspect latch/index pin assembly and reach daily for any broken or missing parts and replace if necessary.
Safety Chains
- Additional safety chains can be added to these trucks and trailers to provide extra security and help prevent these types of incidents. Two 72 inch safety chains (1/2 inch, Grade 70 chain) can be used to connect chain hanger ears to the existing safety chain hanger on the truck. These chain hanger ears are new components that are welded onto the trailer. See below for diagrams.
Related Safety Alerts:
- Log truck spills load, trailer almost separates on highway
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Contact our Transportation Department in Prince George if you require additional information about this incident. Call 1-877-741-1060.
