AL-KO Highline 51.8 SP-A 4-in-1 Self-Propelled Petrol Lawn Mower
AL-KO Highline 51.8 SP-A 4-in-1 Self-Propelled Petrol Lawn Mower AL-KO Highline 51.8 SP-A 4-in-1 Self-Propelled Petrol Lawn Mower
RRP: £429.00
OUR PRICE: £379.00 (inc VAT)

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The AL-KO Highline 51.8 SP-A is a premium quality, multi-functional petrol rotary lawn mower suitable for larger lawns up to 1,800 square metres in size.

The mower features a flexible 4-in-1 function so you can decide whether you want to collect, mulch, side discharge or rear discharge the grass cuttings. Mulch mowing is achieved by simply mounting the mulch insert so the grass clippings are chopped into tiny particles and returned back to the lawn surface to provide natural fertiliser. The practical alternative for longer grass, as found in meadows and orchards, is to side discharge. The seven stage cutting height is centrally adjustable from 30mm to 80mm using a single spring-assisted lever.

The 51cm (20") wide cutter deck benefits from AL-KO's MaxAirflow technology whereby the extra tall steel plate deck and extra large discharge channel significantly increase the airflow. As a result, the grass clippings are not transported at a low level into the grass catcher (as is the case of most standard lawn mowers) but are instead thrown backwards in a high arc and remain at the back. This means the grass catcher is effectively filled from the back, without the discharge channel becoming blocked. An added bonus is the removable service flap for convenient mower maintenance.

The large 70 litre capacity grass collector has a full indicator which alerts when the box is full. EasyClick engagement means the grass catcher can be easily hooked in and out.

An AL-KO Pro 145 air-cooled, four-stroke engine with overhead valve technology produces 139cc of clean, efficient and quiet power. Because the machine is self-propelled, even sloping lawns can be mowed effortlessly, assisted by the extra large rear drive wheels with double ball bearings for extra grip and smooth running.

The AL-KO Highline 51.8 SP-A petrol lawn mower will easily fit in the shed or garage thanks to its upright storage position, which also facilitates cleaning and maintenance of the cutter deck.

Product specification

Brand: AL-KO
Engine: AL-KO
Engine Model: Pro 145
Engine Type: Petrol, 4-stroke, OHV
Displacement: 139cc
Rated Power Output: 2.1kW / 2850rpm
Start Method: Recoil
Throttle Control: No
Propulsion: Self-propelled
Ground Speed: 1-speed
Recommended Lawn Area: Up to 1800m²
Cutter Deck: MAX AIRFLOW steel
Cutting System: 4INONE function: mow, collect, mulch and side discharge
Width of Cut: 51cm / 20"
Minimum Cutting Height: 30mm
Maximum Cutting Height: 80mm
Cutting Height Adjustment: Central, 7 stages
Collection System: Direct collection
Grass Collector: EasyClick plastic grass box
Collector Capacity: 70L
Bag Full Indicator: Standard
Mulch Capable: Yes
Mulch Plug: Standard
Side Deflector: Standard
Handle Type: 2 point, foldable
Wheels - Front: 200mm, ball bearing mounted
Wheels - Rear: 280mm, ball bearing mounted
Weight: 38.3kg
Warranty: 5 years for domestic use (subject to online registration & annual service)
90 days commercial
AL-KO engine

AL-KO Engine

AL-KO has developed a range of new engines that are tried and tested for quality, value and reliability and are Euro 5 compliant. The engine is made by Loncin, is 139cc and produces 2.1kW of power at 2850rpm.

AL-KO overhead valve  

OHV Technology

OHV technology for more performance, less consumption through optimal valve location and design of chamber.

AL-KO quick start system 

Quick Start System

The AL-KO 140 Pro QSS engine features a new Quick Start System making it easier for the user to effortlessly start the powerful engine.


The mower is equipped with a clutch which, when engaged, propels the mower forward, reducing the amount of effort expended by the operator.


4-IN-ONE Function

A multi-function machine, AL-KO's prized 4-in-1 function features mowing, collecting, mulching and side discharge capabilities.

AL-KO Highline MaxAirflow technology


Extra tall, extra large – that's the basis for MaxAirflow technology. This is because the extra tall steel plate deck and extra large discharge channel increase the airflow by 42 per cent. As a result, the grass clippings are not transported at a low level into the grass catcher as in the case of most standard lawnmowers, but are instead thrown backwards in a high arc and remain at the back. This means the grass catcher is effectively filled from the back, without the discharge channel becoming blocked. Another bonus: The removable service flap for convenient mower maintenance.

Full Catcher, Fewer Interruptions

MaxAirflow technology means that the lawn clippings are thrown to the back of the grass catcher, as a result of which it is filled to the top and does not have to be emptied so often.

No Green Fingers

MaxAirflow technology means that it is even possible to mow long, damp grass without leaving clumps behind on the ground or blocking the discharge channel. This means your hands stay cleaner.

AL-KO mower efficient controls

Efficient Controls 

The Highline lawn mower range features efficient controls including a sculpted drive lever to avoid trapping fingers.


AL-KO Service Position

An innovative AL-KO concept, this mower features a unique Service Position which enables the mower to stand on end when the fuel tank is empty.  This allows easy cleaning and maintenance of the underside of the mower deck.

Other Key Features

Large EasyClick grass box with level indicator.

Comfortable, seven stage cutting height is simple to adjust using a single lever.

Extra high drive wheels for added traction and easier turning in long grass.

Ball bearing wheels won't stiffen up over time.

Mulch plug is included.

Main lawn mower body comes fully assembled in the box.


AL-KO petrol lawn mowers are now backed by a five year warranty for domestic use.

Alko lawnmower


Founder Alko Founded in 1931 by Alois Kober as a small metalworking shop in southern Germany, AL-KO has become a global player comprising of more than 50 sites in 30 countries. The AL-KO Group today employs over 4,200 people worldwide covering three business divisions - Vehicle Technology, Garden + Hobby, and Air Technology. All AL-KO employees take great pride in the quality products they manufacture. 

For greater enjoyment in the garden

For more than 50 years, AL-KO has been developing and designing innovative garden tools for an extremely wide range of requirements and applications. Not only do AL-KO tools reflect its many years of expertise in technology and function, they also set new standards in terms of design. 

When the best is expected

With Germany efficiency, AL-KO's research and development engineers create pioneering garden tools from hundreds of individual parts. Materials of the highest quality, ingenious technology, perfect ergonomics and a sure feel for form and deteail make AL-KO's garden tools unmistakable.

The rigourous quality requirement that characterises the AL-KO band is guaranteed through its comprehensive technology programme that is consistently planned and implemented by AL-KO development engineers, designers and technicias - from the first design, to prototype construction and the end product.

Why not take the plunge into the world of AL-KO and get to know its high-quality products - without doubt you will find just the right implement for your requirements. AL-KO has everything you need for the garden, whether you are mowing, trimming, shredding, mulching, scarifying, lawn raking, cultivating, splitting or clearing ... 


All machines come with a two year warranty, following this machines have an extended warranty depending on the range and annual servicing by an authorised AL-KO dealer.

AL-KO Warranty

Solo by AL-KO

AL-KO has recently acquired Sindelfingen-based SOLO Kleinmotoren GmbH to strengthen its range of garden machinery. The existing AL-KO range is being expanded with petrol chainsaws and trimmers, providing customers with expertise and strong, tradition-rich brands in one product range.

 AL-KO factory


Click to view AL-KO Garden Technology brochure

Alko german

Add review
5 Star Rating
Apr 07 2018
Can't rate this machine too highly. Compared to our previous petrol mower which was pretty good, this one does all the work in half the time. Engine starts first time, controls are easy. Also very happy with Green reaper for the speedy service and for delivering when they said they would.