John Deere 850J LGP dozer

By: Tim Dittmer, Photography by: Tim Dittmer

Date: 02.06.2011

The John Deere 850J LGP is a customised dozer made to handles the rigours of a landfill site that handles over 100,000 tonnes.

Note the long undercarriage on the John Deere 850J LGP dozer.

Large swinging panels give good access to the hydraulic filters
Ergonomic controls are simple and smooth to use
Feels surefooted and stable
Tiltable cab
Long track frame
Plenty of power from 200hp engine and hydrostatic drive

Wellington City Council's Southern Landfill handles over 100,000 tonnes of general waste and 20 to 30,000 tonnes of additional waste that is recycled per year. They also make compost out of the organic matter that is then on-sold.

The John Deere 850J LGP bulldozer works covering the rubbish at the end of each day with a layer of rock and dirt and then uncovering it in the morning. It also does some ripping and other dozing work in the landfill.

Drive train

A John Deere Power Tech Plus 6090HT six-cylinder engine provides 200hp to the hydraulic pumps. The turbocharged diesel engine twists out 915Nm of torque and is certified to meet Tier 3 emission standards. Each track has its own variable displacement piston pump and motor, allowing counter rotation and full powered turns. The drive system can develop up to 459 bar (6650 psi), which in turn gives a whopping 344Kn of drawbar pull and can move the 21-tonne beast at a top speed of 10.1kph. The double reduction planetary final drives are independently mounted from the track frames and blade arm mounts to help isolate them from shock loads.

A separate pump delivers 174 litres per minute for the blade and ripper controls, but the bulldozer can also be specified with a high flow pump and cooler for powering winches.

Design and maintenance

Both fuel and oil filters are easy to get at along with the air cleaner that is above the engine. Daily checks can be done from one side.

The variable-speed fan automatically adjusts to provide the right amount of cooling. It can also be programmed to automatically reverse to help avoid clogging.

Behind the rear panels are the hydraulic filters, tanks and batteries, separate hydraulic and hydrostatic systems eliminate cross contamination. All the filters are remote mounted and vertical, allowing them to be changed with minimal mess.

Another excellent feature is the tiltable cab. Once a few bolts are removed, the ROPS cab simply pumps up by a small inbuilt hand pump to allow full access into the guts of the 850. Heavy duty belly guards are fitted under the machine along with full length track guards.

Cab and controls

Access to the cab is easy thanks to large handrails and plenty of space to stand. The seat is comfortable; there are large arm rests with control levers placed at the ends. It's a nice basic interior with everything well laid out. Visibility is excellent all round; the bottom of the blade can be seen.

The dash is easy to read and houses five gauges: coolant, transmission and hydraulic temperature, engine oil pressure and a fuel gauge. A digital screen displays an hour clock, rev counter and the selected ground speed. The left joystick controls the direction and steers the dozer; the right joystick operates the blade. A small lever along side controls the rear rippers. The decelerator pedal not only governs the engine revs but when fully depressed the brakes are automatically applied.

Performance and handling

This John Deere 850J is extremely comfortable to operate. The position of the seat, along with the higher arm rests and joysticks make you feel secure and stable.

A small dial to the left of the left joystick controls the engine revs - even with it wound to full throttle the cab remained at a nice noise level.

To control the dozer you simply push the left joystick forward until it clicks in to its detent then let the decelerator off and you're away. Steering is achieved by moving the same joystick sideways; the more it is moved the tighter the turn, and by moving it right the way across allows you to counter rotate the John Deere on the spot, giving excellent manoeuvrability.

Being hydrostatic drive means there are no gears to change, the speed of the dozer is adjusted by clicking up or down on the thumb-operated buttons on the left joystick, which in turn change the angle on the swash plates in the variable displacement piston pumps. More oil at less pressure gives a faster speed but less track power, less oil at more pressure gives slower speed with strong track power.

I line up a pile of dirt, lower the blade and let the 850J bury in. It effortlessly bowls through the pile. The dirt builds up in front and even spews over the top of the blade with hardly any let up in speed.

Full powered turns are another feature of the hydrostatic transmission, which keeps both tracks driving while turning by slowing one track or increasing the speed on the opposite side. It helps to push more material while turning on a gradual turn and is great when working on a cross slope but brings little benefit when turning tightly. Being a LGP (low ground pressure) model means it has a longer undercarriage than standard and even when I got too greedy pushing the fully loaded blade it easily spun its tracks, barely working the 200hp engine.

The blade is very smooth to operate and it has a great range of movement up and down with a high lift height. It also benefits from twin tilt rams that not only give pitch adjustment but also increase the tilt range of the blade.

What I really like about the 850J's hydrostatic transmission is that when you decelerate fully or shift it to neutral it stops and sits there because the brakes come on automatically just like an excavator. You don't have to hold it on the torque converter or stand on brake pedals when working on steep hills.

I backed the John Deere up a fairly steep hill until it ran out of traction, decelerated shifted the direction lever forward, and with little engine revs slowly descended back down, fully controlled and with no coasting. Because the hydrostatic drive is infinitely variable the whole procedure was very smooth and I was in total control at any speed and with any engine revs.

The verdict

I was extremely impressed with the John Deere 850J LGP bulldozer. I found it to be a well designed machine with not only the operator in mind but also the mechanic. Everything seemed to be in a logical place in the servicing side of it but particularly in the cab.

The controls are smooth and precise and the whole operation feels natural, comfortable, stable and safe. I was in awe of the hydrostatic transmission, it did exactly what I wanted when I wanted and made operating the machine a pleasure.

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