The Black Forest region of Germany is home to many well-known companies such as Bosch and Mercedes Benz. It is also home to one of the earthmoving world’s biggest surprises, Lehnhoff.
In a small blacksmith’s shop near Baden-Baden in 1960, Ernst Gunter Lehnhoff began repairing buckets and machine tools for local industries before forming his own company in 1962. The new company was focussed on meeting the demands of the quarrying industries and their need for high-carbon steel in earthmoving applications. This was quickly followed by the manufacturing of customer specific backhoe buckets in 1966 and the invention of the first tilting bucket in 1969. In 1984 the first tie-in with Komatsu came along with Lehnhoff becoming an approved supplier of hitches and buckets to the Japanese company.
Constant expansion and development throughout the 1980’s saw the company produce their first manual quick coupler which has pushed them to become the number one seller for couplers in excavators under 10 tonnes throughout Germany, Austria and Switzerland. Not content with dominating this huge market further developments have seen Lehnhoff design and produce a massive range of excavator attachments and buckets for carriers up to 130 tonnes.
The advent of hydraulic hitches across Europe saw the company launch Lehmatic quick coupler range, again with capacities from 2-130 tonnes. Where the Lehnhoff range differs from many manufacturers is the number of models required to fit such a broad spectrum of carriers. Just ten couplers are needed to cover this large weight range with seven adapter heads for buckets and other attachments meaning that a contractor with Komatsu PC210 and a Komatsu PC 360 can be utilising the same attachments resulting in lower investment costs especially when it comes to hammers or any other costly hydraulic attachments. This versatility has enabled the manufacturer to turn a single machine into a cost effective tool carrier at a fraction of the cost.
Where many quick couplers are designed to pick up on the attachment’s pins, the Lehmatic system picks up on the front pin only and uses a pair of conical pins at the rear of the hitch to positively engage with an adapter plate on the rear of the attachment’s headstock. The precision engineering on both the hitch and headstock allows for a snug fit when aligning both units together. The slightly angled receiver plate and the angle on the rear of the hitch stops the attachment from rattling unlike a standard PUP hitch. With the twin conical pins inserted into the plate along with a non-return valve and permanent pressurisation there is no chance of the attachment being removed from the excavator even under a catastrophic hydraulic failure.
This system is also employed on the company’s Variolock system which sees the hitch being fitted with a valve block to transfer hydraulic fluid and electrical connections through the hitch to the attachment resulting in the safe and quick changeover of tools in under 30 seconds. Whilst some similar systems rely on the male and female valve blocks being pushed together to form a seal, the Variolock system presses the two blocks together under pressure meaning fewer moving parts and less maintenance issues. Where the Variolock and Lehmatic differ is in the pinned connection at the rear of the hitch. To ensure the seal between the two valve blocks is good, the rear conical pins are chamfered at their top edge and this precision machine work ensures there is sufficient pressure at all times to engage the two blocks.
We were invited along to the company’s production facility just outside Baden-Baden to see the manufacturing process involved in bringing these hitches to the market. With sales figures increasing year on year since the recession, the company has invested heavily in developing new machining facilities at the factory in a bid to reduce lead time. The state-of-the-art facility now produces over 3000 hitches per year along with 8000 buckets and attachments.
Using only the best quality Hardox and Weldox steels, the company cuts, bends, welds and machines everything in-house to ensure the quality of the finished product is second-to-none. The quality of the parts coming from the computer controlled plasma cutting benches is first class with all parts chamfered to allow a proper fillet weld to be undertaken. “We try and reduce the amount of butt welds we introduce to a product as a fillet weld is far stronger and durable.” Explains Sebastian Denniston, Lehnhoff’s Product Manager. Whether it is a hitch or a bucket, the manufacturing of each item is strictly controlled with the initial tack welding of each unit in a specific jig before it is passed onto robot welders for the final full welding.
In typically German fashion, the completed carcass of a hitch is checked before passing on to the next process to ensure the quality of the product. Painting is also carried out at the factory with the standard blue or red colours being finished with a hard wearing coat.
Whilst the factory manufactures new equipment, it also offers a full refurbishment and rebuilding service to its customers. “We are able to bring a worn hitch back into the facility and using our skilled and experienced welders, we are able to build up the front pins and re-bore them back to the original specification.” Sebastian explains “A typical re-build will cost a third of the price of a new hitch meaning the customer doesn’t have to invest in a new hitch.” Whilst this re-building service is impressive, shipping costs for UK customers may make it prohibitive. To this end, Lehnhoff’s UK dealer, Worsley Plant from Middlewich is looking to offer the same service in-house at their facility in Cheshire.
Whilst hitches are the most notable of products manufactured by the company, where would a hitch be without a bucket or attachment to go on the end of it?
As with the hitches, buckets to suit all sizes are manufactured in-house and are built to the same high standards as the hitches are. Manufactured from the finest steels, the range of buckets is almost endless. Standard and bespoke sizes and designs are catered for with many hitch buyers taking a range of buckets with the hitch. “The buckets are designed to offer the shortest pin to pin measurements and offer the greatest all round productivity and reliability possible.” Sebastian said. One of the biggest and most popular ranges produced is the tilting ditching bucket. A common sight on European machines, the tilting ditcher, in a variety of widths, is seen as a standard bucket in Europe.
The close tie-in with Komatsu has seen the Birtley based manufacturer adopting the Lehnhoff tilting ditching bucket for its range of intelligent excavators.
Article written by Paul Argent of RPA Media Services