Challenge

An underground, hardrock mine operation observed an uptick in the mean time between transmission failures on their mobile equipment. The expected life is 25,000 hours, but they are only averaging approximately 20,000 hours.  They were losing nearly a year of operation on every transmission.  It also means they are spending money on transmissions earlier than planned.  Maintenance is performing the prescribed PMs, so the issue was not being resolved with Planned Maintenance.  

This has led to increased machine downtime, unplanned maintenance activities, and delays in production. The maintenance manager suspects operator error, however they need to prove this to be the case before corrective action can be taken. They require a system that can identify instances of transmission abuse within their 25 vehicle fleet, focusing on LHDs and haul trucks, and provide the shift time and operator of the vehicle. Due to the conditions of the mine, they require a solution that can collect the data and deliver it even in instances of irregular network connectivity.  

Solution

To address this problem the customer approached Symboticware and requested that they utilize data collected by the SymBot to determine whether transmission abuse had occurred. Two states were identified as constituting transmission abuse:

State 1: Downshift Violation

In this state the operator shifts from one gear to a lower gear, causing strain to the engine. For example, an operator is in third gear and shifts down to second while the engine is heavily loaded. This forced downshift at high engine load leads to excessive wear on transmission friction components such as bands and clutches. This scenario often occurs when an operator attempts to get a fuller bucket by slamming into a muck pile.

State 2: Neutral Shift Violation

In this state the operator changes from one direction to another, without first stopping in neutral. For example, the vehicle is moving forward, the operator is drifting to a stop and brings the selector to reverse gear without reaching a full stop, causing significant strain on the engine.

Implementation

Using the above states, Symboticware prepared an algorithm to detect each using selected gear, engine percent load ( collected from the machine’s engine ECU), and ground speed (collected from Symboticware’s Speed Guard product). With this instances of both types of alert were compiled into a comprehensive report, and an email alert was set up to notify key stakeholders of any further detected instances of these events. Further to this, a tag in/tag out system was installed on each vehicle, with each operator issued a distinct keycard they swiped at the start at each shift. A record of this card swipe was logged by the SymBot, and this information was included in the report of each incident of transmission abuse. 

The SymBot was chosen to collect the data due to its capacity to record data out of coverage and report data once network connectivity is restored, and because of its ability to interface with all of these discrete systems. 

Impact

Once notified of the scope of these incidents, and through the identification of problem operators, management was able to address the issue. The chart below shows the breakdown of transmission abuse events detected for the full twenty unit fleet, per week, prior to the implementation of the system and afterwards. In grey is the downshift violation, and on top in blue the neutral shift violations. The red line indicates the time at which the transmission abuse alert was implemented.

Following the implementation of the alerting system, problematic operators were identified for retraining in the proper operation of the equipment and a steady decline in cases was observed. Approximately 95% of incidents were curtailed within two months of deploying the solution and instigating retraining and disciplinary actions for repeat offenders. 

With this reduction in transmission abuse incidents a parallel decrease in unexpected transmission failures was also seen. After the project, they were able to eliminate 95% of operator abusive shifts and were averaging over 25,000 hours per transmission--more than the expected life.  The cost savings paid for the entire telemetry solution within three months.

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