Case Study
Case 821G XR centre pivot repair: bore welding and line boring in the workshop
How J Hull Plant Engineers restored the centre pivot bore of a Case 821G XR wheel loader to size in its own workshop, with bore welding and line boring carried out in a single set-up by a Dual System portable line boring machine.
Client
J Hull Plant Engineers Ltd, Poulton-le-Fylde, Lancashire (United Kingdom)
Vehicle involved
Case 821G XR articulated wheel loader, approx. 18–19 t, approx. 157 kW
Machine used
LBM250 Dual System, supplied by Maucotools UK
Key result
Approx. Ø150 mm bore rebuilt and machined back to size in the workshop
01 — The protagonist
The protagonist: J Hull Plant Engineers
J Hull Plant Engineers is a service and repair workshop for earthmoving plant in the North West of England. It chose one of Maucotools' Dual System portable line boring machines, supplied by Maucotools UK, to bring worn-bore repairs in-house. The job on the Case 821G XR was one of the first carried out with the new machine.
approx. 18–19 t
Operating weight
Case 821G XR articulated wheel loader (manufacturer's published data).
approx. 157 kW
Engine power
Manufacturer's published data.
approx. Ø150 mm
Bore machined
Centre pivot bearing bore, in the pivot plate.
02 — The challenge
The challenge
A Case 821G XR, an articulated wheel loader of approx. 18–19 tonnes, needed its centre pivot bearing repaired: the joint where the front and rear frames turn against each other, and which takes the loads of every steering movement. To reach it, the machine was split in two in the workshop.
Starting point
With the bearing removed, the bore in the pivot plate, approx. Ø150 mm, was also worn and out of tolerance.
The risk
Fitting a new bearing in a bore that is no longer round soon brings back play, knocks when steering and fresh wear.
The requirement
Rebuild the bore and machine it back to size before fitting the new bearing.
03 — The solution
The Maucotools solution
The LBM250 Dual System portable line boring machine was mounted directly on the pivot plate, with the axis vertical: rotation module on top, feed module below.
The Dual System advantage
With the Dual System the same machine first carries out automatic bore welding inside the bore and then line bores it to size, without being removed or re-centred between the two steps. When this pays off is explained in our guide to the portable line boring and welding machine.
All in the workshop
The frame never had to leave the workshop: no transfer to a machine shop to rebuild the bore.
04 — Procedure
Repair procedure
Splitting and dismantling
Splitting the machine at the centre pivot and removing the worn bearing.
Cleaning and inspection
Cleaning and inspecting the bore.
Mounting and centring
Mounting and centring the line boring machine on the pivot plate bore.
Weld overlay
Automatic spiral weld overlay along the full length of the bore.
Line boring to size
Line boring to size for the fit with the new bearing.
Inspection and reassembly
Dimensional check, fitting the bearing and reassembling the machine.
05 — Results
Results obtained
Centre pivot bore
approx. Ø150 mm
Rebuilt and machined back to size in the workshop
Weld overlay and boring
Single set-up
No re-centring between the two steps
Repair
Complete repair
Bore rebuilt, not just the bearing replaced
Organisation
In-house
Job handled with the workshop's own machine
The approx. Ø150 mm bore was rebuilt and machined back to size without sending the frame to a machine shop: a complete repair of the centre pivot bearing, not just the replacement of the worn part. It is a job J Hull Plant Engineers now handles in-house with its own machine. More repairs are collected in our Maucotools case studies.
06 — In the field
In-the-field documentation
The stages of the repair in the J Hull Plant Engineers workshop: mounting the machine on the centre pivot, bore welding and line boring to size. Photos: J Hull Plant Engineers.
Got a worn bore to rebuild?
Centre pivots, pins and bearing bores on earthmoving plant: Maucotools' engineers will help you choose the right set-up for weld overlay and line boring, in the workshop or on site.