Menzi Muck A91 4x4 Plus excavator

By: Tim Dittmer, Photography by: Tim Dittmer

Date: 10.02.2011

The Menzi Muck A91 4x4 Plus excavator is one-of-a-kind: capable of safely working on the steepest of grades, with a diverse range of attachments.1

What is it? Why, it's a Menzi Muck A91 4x4 Plus excavator.

Extreme flexibility and mobility
Well laid out and comfortable cab
Impressive ground clearance
Wide range of attchments
Easy to service

Paul McCready of McCready Engineering Ltd, located just north of Wellington, owns and operates a Menzi Muck A91 4x4 Plus excavator, possibly the only machine from this Swiss manufacturer in New Zealand.

In 2004, Paul spotted a Menzi Muck at the Bauma trade expo in Europe and decided there was a market here. In 2006, the wheeled spider arrived and was put to work.

Engine and hydraulics

A huge 133hp is churned out of the turbocharged John Deere four-cylinder engine, mated to two variable displacement piston pumps. The first expels up to 245L/min for the main machine functions, including powering the attachments with up to 150L/min, while the second delivers a maximum of 135L/min and is dedicated to driving the four large wheels.

Maintenance and servicing

With the machine sprawled out on the ground it's easy to make all the daily checks and carry out the 500-hour services. The rear hood lifts up to reveal the engine, and all the filters are easy to get at. On the left is the engine's 130-litre lunch box. There is an additional 200-litre diesel tank located in the chassis beneath the slew ring. There is also an onboard transfer pump to refresh the top tank.

A hand pump mounted in the rear tilts the ROPS, FOPS and OPS cab to uncover hydraulic hoses. It is also equipped with an auto greasing system. The right side panel lifts up to expose the large cooling system, hydraulic tank and another control bank. Access is good, though the air filter housing has to be removed when replacing the batteries.

The small left panel unclips to provide closer inspection of the pumps.

Performance and handling

All four legs are fully adjustable in every direction; the front two wheels steer the Menzi while the rear two are fixed. It is also fitted with two individually controlled stabiliser feet at the rear.

With the four legs down, the A91 can wade through water over two metres deep. Capable of comfortably working on a slope of 45-degrees and a cross slope of 35-degrees, it has also got a winch with a line pull of about eight-tonne mounted to the chassis for extra assistance on steep terrain.

Paul stands the Menzi on its rear feet and shows the flexible positions it can achieve. He turns the machine and aims it at a steep hill (46-degrees). It is more effective to push the Menzi up hills so Paul slews to the rear, and with the wheels driving, uses the bucket to help the A91 negotiate the hill.

A telescopic dipper arm brings huge benefits assisting the manoeuvre of the machine over and around obstacles and also increasing the bucket range. Upon stretching to maximum reach the rear stabiliser feet are pushed into the ground to help hold the A91 in position while the bucket takes another bite.

My turn

There are two joysticks, each capable of up to 25 functions depending on the specification chosen. In this case, each lever is fitted with two four-way toggle switches, one two-way rocker switch, six buttons and two trigger buttons. The two joysticks operate the boom, arm, bucket and slew just like a standard excavator. The right legs are controlled via the two toggle switches located on the right joystick and the left are vice versa. Each toggle controls the up, down, left and right functions of each leg.

After adjusting the width of the machine base the front wheels need to be realigned to track parallel, this is done by squeezing the left trigger button and rocking the front leg control left or right to individually move each wheel. To steer both wheels simultaneously, the right trigger button is squeezed and the bucket crowd joystick becomes the steering lever. Slewing around to the rear makes it all back to front and the brain meltdown begins. A button on top of each joystick actuates the tilting quick hitch. The two rocker switches control the fold-down feet at the rear. Then there are four pedals, one for each of the following: extendable dipper arm, winch, driving wheels (forward/reverse) and high flow attachment.

The undercarriage can adjust from 2.3-metres to over 5.5-metres. Comfort and visibility get the big tick but, as Paul explains, "depending on the position of the machine, sometimes you can't see all the legs, making delicate placing of the wheels tricky, though this can be easily overcome by having a spotter giving instructions on a radio."

Feel free to ask a question about this story or leave a comment on the Deals On Wheels page.