More power to the Stoll elbow

in Reviews. 20 Jan 2010. 418 views.

The Robust FZ+ 40 front end loader from Stoll follows on from the F 35 HDPM. In tests the new model produced similar results to its predecessor; in practice the operator gets a better view, and sundry details have been tidied up

 

Is it possible to have too much of a good thing? After previous front loader comparison and an introduction to Stoll’s FZ+ 40, this time we’re running a much more detailed rule over a pre-production version of the FZ+ 40. It’s in the middle of Stoll’s Robust FZ range and should be a good match for UK mixed farms.

The FZ+ 40 came on stream this spring, suiting tractors from 90hp up to 140hp. For this test it’s carried by a Claas Ares 557. The newer unit has a little more lift capacity but physically the same spec as the F 35 HDPM featured in previous profi tests; that is, a block coupler for the hydraulic hoses, a joystick linked by cable to the spools, tractor brackets with rear axle support and bonnet guards.

Our first drive covered the FZ+ design in detail, highlighting the way the operator’s forward view is improved by routing both the hydraulic lines and the first section of parallel lift linkage inside the arms. While we can’t assess the materials used to make the FZ+ 40, its design and construction suggest a strong and potentially durable unit. Pivot pin diameters and lengths are generous, and the loader itself, without attachment, is weighty at 600 – 100kg more than the F 35 HDPM, and 20kg more than Stoll claims for the basic unit. Further detail is listed in the Test Assessments panel.

The facts

Now for some figures. Maximum lift force at 30cm above ground level was measured at nearly 2400daN – that’s good. Continuous lift force came out at almost 2100daN, which is excellent. These figures pretty much parallel the F 35 HDPM’s results. Break-out force – the maximum available to crowd an attachment, and
a measure of tilt/crowd ram capacity – needs to be more than 2,000daN for good loader performance. We measured almost 2100daN (so no problem there), but this is substantially less than generated by the F 35 HDPM in the group test. Stoll says it deliberately limited the FZ+ 40’s performance in this area to avoid overloading the tractor’s tyres and front axle.

Lift height

Maximum lift height (measured at the carriage pivot) is 4.10m, top-notch for this class of loader and 10cm higher than the F 35 HDPM managed. But the advantage is not carried through into its maximum reach over a trailer and maximum dump height; we found the FZ+ 40 could clear a 3.85m trailer and its bucket edge was 3.19m from the ground when tipped to 40°. These are good figures, but with the same bucket the previously tested F 35 HDPM provides 10cm more clearance and 2cm less dump height. The floor of the bucket we used measured 81cm from front to back, which is fairly long. Fit a shorter bucket to the F 35, and its dump height will go up in step.

Tipping reach

A loader’s tipping reach is the distance between the bucket lip and the front of the tractor, measured with the bucket tipped at 40°. It’s down to boom length, attachment pivot position and lift height, and will determine how well the loader copes with large trailers – whether it can reach in in comfort. The minimum is reckoned to be 1m; we measured 1.08m on the test FZ+ 40. Digging depth with the bucket level came out at a healthy 23cm, a figure that’s easily increased by tipping the attachment.

Tip and crowd angles make or break a loader. On the whole, the FZ+ 40 does well here; at ground level the crowd angle was an excellent 53° so bucket filling is no problem, while tip angle at max lift was a good 51°. Since our test Stoll has introduced new attachments and now claims angles of 48.5° crowd and 55.5° dump. On top of this, pushing a joystick button brings in “auto-curl”, pulling in the rams more and crowding the attachment back by another 20° to maximise filling.

Stoll’s Z-kinematic system aims to keep the loader attachment level during boom
movement. Performance is OK; we reckon that the bucket crowded by +4° over the loader’s full lift, which is not enough to spill grain. With pallet forks, the figure was +6°.

Fast cycle time

The other cornerstone of effective loader performance is a fast cycle time. The test FZ+ 40’s boom moves at a brisk 0.87m/s going up, and 1.21m/s coming down. Crowding and dumping are respectable too, at 59°/s during crowd and 64°/s
during dump; the latter is achieved by triggering the carriage to free-fall from a joystick button. If powered dump is used, the rate is a more pedestrian but still satisfactory 49°/s.

When it comes to boom suspension, Stoll is navigating uncharted waters. Not for it the traditional nitrogen spheres; instead, a horizontal piston arrangement, much like a hydraulic ram, is concealed within the arms’ lower cross-member. The Stoll claim is that the FZ set-up gives better cushioning of any light shocks while letting the suspension self-adjust to cope with heavier loads and bigger deflections. Suspension shut-off is manual with an electric option. So does the new Stoll approach work? Yes, on the whole, it does. Boom suspension is subjectively effective, both when travelling empty and with a considerable 1000kg load on board, with movement at the carriage pivot pin a generous 6cm.

The verdict

The Stoll Robust FZ+ 40 is a modern, potentially sturdy front loader with appealing design and largely excellent performance. Driver visibility over the booms is good, thanks in part to the Z-kinematic arrangement. Most components are out of sight and protected.

Drawbacks? There is really only one. Stoll sticks with the traditional hook-and-pin for coupling loader and tractor, which has long since been bypassed by the semi-automatic set-ups of other brands.

The Robust FZ+ 40 is a modern loader. Hydraulic lines are largely protected, and Stoll’s Z-kinematic set-up handles parallel lifting. Photos: ST.

Attachment angle is shown by this telescopic rod, zeroed without having to resort to tools

Where possible, oil lines are tucked under the arms. Valves are hidden under a cover (here removed), while the boom suspension cylinder is inside the oval-section cross-member.

Pluses and minuses

+ The Hydro-Lock hose coupling is permanently pressurised and has a revised locking indicator

+ All pivots are replaceable, greaseable and pins are locked against turning

+ The new paint scheme looks good and is well-finished

– The loader’s electrics are coupled separately with a seven-pin socket

– There is no indicator to show the tip angle required to access the Z-kinematic’s inner joints

–Boom brackets can mark the tractor’s mudguards

Available oil, 3rd circuit ++

Grading system:

++ = very good; + = good; 0 = average; — = below average; — — = poor; G = not available/not seen

Dump speed ⁵⁾ 49°/s, 64°/s