Finning rebuilds Cat 775D off-highway truck - VIDEO

A Lafarge Cat 775D off-highway truck, which has worked for 10 years and over 25,000 hours, has been completely rebuilt in just three months at Finning’s specialist rebuild centre in Chesterfield. The video below explains the process, and includes time-lapse footage of the rebuild. 

The rebuild process explained

Graham Turner, Finning product support sales representative: “Having worked with Lafarge to help them maintain the Cat 775D over its lifecycle, we had a good knowledge of the machine and following a detailed inspection from our rebuild team based at our Chesterfield branch, we were able to confirm that a rebuild was both financially worth while and practically possible.

“Because Caterpillar machines are ‘built to be rebuilt’ we were able to give Lafarge two main options to extend the life of the Cat 775D. The first was a Finning Dealer Rebuild, where our engineers work closely with the customer to identify the core parts of the machine that need to be replaced or repaired to extend the life.

“In some circumstances, customers may opt for an engine and transmission change out and general repair work. Of course you can never know how much work is needed until the machine is stripped down.

“If however you want to give your machine a truly new lease of life, like Lafarge with its Cat 775D, the option to take is a Caterpillar Certified Rebuild, (CCR) which is a total rebuild approach, specifically written for every machine and followed to the letter."

Timing is crucial

“Spotting the right time to make the rebuild decision is crucial, as if you wait too long there is the possibility of a major component failure that would add considerable cost to the process. Managing the programme of taking a key machine out of operation for up to three months is also important to minimise the impact on quarry production levels.

"Following a meticulous maintenance regime and keeping a close eye on equipment can help to make the decision easier as key component wear can be spotted more easily.”

Inspection time

Once Lafarge made the decision to rebuild its Cat 775D the first part of the rebuild programme, the inspection process was undertaken by Finning rebuild specialist. 

Obvious points like leaks from suspension legs were simple to spot, but in order to complete a full inspection the Cat 775D had to undergo a thorough cleaning process. The next step was to complete the inspection report and cost the rebuild.

The strip down

Once costs had been agreed with Lafarge and a window for the work to begin arranged, the Cat 775D was removed from site to the Finning rebuild centre in Chesterfield for dismantling.

The next stage of the programme was to strip down the machine to the main chassis. The first part of this process was the removal of the 64t capacity skip, which would be inspected, repaired and re-sprayed later on in the programme before it was reunited with the main body of the truck.

The skip removal allowed the main body of the truck to be moved into the workshop. All parts and bodywork were then removed with those parts that are no longer required, housed in the Finning yard for recycling.

Dealing with metal work fatigue

With a bare chassis, the process of dealing with metal fatigue was able to commence, with all areas fully inspected and decisions made as to the replacement, repair and treatment or reinforcement required to support the truck through the next 15,000 hours of its expected life.

Once the cabin, engine, transmission, suspension cylinders and other key parts of the truck were removed, the chassis was then shot blasted and thoroughly inspected for cracks and metal fatigue.

With remedial work already undertaken on the Cat 775D to strengthen the chassis, Finning engineers fitted improved plating to all four suspension leg attachment points in addition to replacing side panelling parts to ensure the chassis strength was capable of withstanding another 15,000 hours of work.

Other mid-life remedial work, including spot welding was inspected and where required necessary work was undertaken to strengthen or rework previous repairs.

Tight schedule

Working to a tight schedule it was important for the Finning team to identify the parts that need the most work at the start of the process.

With CCR there are certain parts that automatically have to be replaced, so these parts were ordered into the workshop before the truck arrived, to prevent any parts sourcing delays. In the case of the Cat 775D, the years of hard work lead to gear wear on the differential with the teeth on the gears wearing to a point where a replacement unit was required. 

Knowing that this was the case at the inspection stage, Finning were able to order a service exchange part from its Component Rebuild Centre, so that there was no downtime in the wait for it to arrive.

Essential Rebuild Items

With any rebuild, one of the most essential items is the engine. The Cat V12 engine used to power the 775D was therefore meticulously rebuilt with every part inspected and either replaced or refurbished.

In the case of engine rebuilds, as a matter of course pistons, bearings and cylinder liners were replaced along with filters, hoses and other parts.

In a similar fashion, core items like the transmission, torque converter and differential were replaced with refurbished units.

New parts play a major role

With 25,000 hours on the Cat 775D’s clock, it was inevitable that the wear on some parts was beyond repair.

One such part identified in the inspection process was the hydraulic pump, as when it was opened up it was clear that the scoring of the bore was too much for the part to be repaired.

Similarly due to working within a limestone quarry, corrosion was unavoidable, with the main skip lift cylinder, a very important part, critical to the operation of the Cat 775D also replaced during the rebuild.

Safety 

With safety standards for access and egress improving with every new model brought onto the market, Lafarge took the opportunity with the rebuild to improve safety standards for the driver, by asking Finning to design and retrofit a new staircase system.

Replacing the vertical ladder previously used, the new staircase runs diagonally across the front of the vehicle with handrails assisting the drivers accent and a lower 3ft step section able to be hydraulically pivoted clear to prevent it making contact with the ground.

In a similar fashion the cab was totally refurbished, with a new improved seat, adding to the driver comfort and a CCTV system installed to aid with reversing.

Back to work

With a complete new paint job and all of the new additions, the Cat 775D was given new tyres to complete the transformation, with the old ones reused on other Off Highway Trucks in the Lafarge fleet.

In total 20 Finning staff played a part in the rebuild, with Lafarge opting for the truck to shed its old Redland green for the traditional Caterpillar yellow. 

Now working at the Lafarge Whitwell Quarry, the Cat 775D is already well on its way to clocking up its expected 15,000 hours worth of new life.