The afternoon after a rain, the paddy looks dry. Put a boot on it and you sink to the ankle. The operator lifts the header, pushes the throttle to the stop, and the tracks churn two holes in the mud without moving the machine a metre. That is where the shift ends.

Ask ten operators why a harvester cannot get over a ridge and you will get ten answers, most of them about the machine. In the field the causes usually sit in four places: how much grip the ground can give, where the weight is sitting, whether the drive still has pressure behind it, and whether the machine physically fits over the ridge. Two minutes at the headland tells you which of the four you are dealing with. Draining the hydraulic tank does not.

What follows is the order we use: identify the type of failure, then check the cause, then act. Everything here can be done in the field. Whether you need a different machine or a different field is a separate question, and it comes at the end.

1. Four different failures behind one phrase

Every operator calls it “it won't go up”. It is four different failures, and each one needs a different response.

Tracks turning, machine stationary. The mud is being cut open and the track spins in place. That is traction: ground, track or weight.

It moves, but slows down and the engine note drops. Power or transmission - hot hydraulic oil, a clogged filter, a slipping belt, a dragging clutch.

The nose stops at the ridge and the header scrapes soil. That is geometry: ridge height, ground clearance, header position, approach angle.

It veers to one side on the slope, the nose lifts, one track loses contact. That is balance: centre of gravity, cross-slope, ballast, uneven track tension.

Getting the category wrong costs time. Opening the throttle on a spinning track only churns the mud into a deeper hole. Laying planks under a machine that has lost hydraulic pressure changes nothing. Watch first, then work.

2. Traction: the layer between track and ground

Track tension comes first. Most rubber-track machines want somewhere around 10-20 mm of sag at the middle of the track, measured the way their manual describes. Run it loose and the drive sprocket ratchets over the links - a sharp crack you hear only under load, which means exactly when you are climbing. Run it tight and rolling resistance rises; idlers, pins and bushings wear early. In wet, soft soil, set it one notch tighter than the dry-field setting.

Worn cleats are the quiet version of the same problem. Once the grousers are down to about half their original height, the track behaves like a flat-soled boot on wet clay. Check the sprocket teeth and the link holes for bright wear marks, and look for teeth that have gone sharp. Both wear slowly, which is why most people notice only after the ratcheting starts.

Then there is the straw. After straw return the surface is a wet mat, and a track on a wet mat slides. Where you know you will cross repeatedly, leave stubble 15-20 cm tall and let the tracks run on the stubble rows instead of the loose straw.

Soil moisture decides more than any adjustment. Squeeze a handful: if it holds a ball and the ball survives a drop to the ground, bearing capacity is already low, and a machine with high ground pressure should stay out. Sandy loam drains in a day, clay takes two or three. The same “day after rain” is two different fields.

For wheeled machines add tyre pressure, tread depth and duals. Wet paddy is not wheeled territory, and forcing it only digs deeper.

3. Weight, balance, and a full grain tank

The cutter bar sits a metre or more ahead of the front axle, so an empty machine already carries its weight forward. On a slope the weight shifts back and up, the front idler loses pressure, steering gets lazy and the climb gets harder. This is why the same machine feels light on flat ground and like a different machine on a bank.

A full tank is the most common self-inflicted cause. At eight or nine tenths full, several hundred kilos to well over a tonne of grain sits high and rearward, and part of your traction goes into carrying it. Unload into the trailer before the climb. It costs five minutes and beats every driving trick in this article.

Ballast depends on the ground. On firm soil a rear counterweight helps. In deep mud it presses the machine further in. The working rule is simple: as mud gets deeper, ground pressure has to fall, never rise - tracked machines in soft paddy generally stay near or below 0.035 MPa. Weight added to a sinking machine makes it sink faster.

One more load people forget: the header, reel and chopper. Lift the header and disengage its drive before the climb. The drum keeps turning at a fraction of the load and you get the margin back.

4. Power and transmission: where the push disappears

On an HST machine the travel pump works hardest on a slope. Once hydraulic oil passes about 80 degrees C, viscosity drops, internal leakage rises, and the symptom is exactly what the operator reports: the steeper the bank, the slower it crawls, until it stops. Check oil temperature, level and filter, then look at the cooler. In paddy work the fins are usually packed with mud, and a single cleaning often brings the machine back.

Belts announce themselves: rubber smell, a squeal, a glazed pulley face. Check tensioners and any oil on the pulley, on both the travel and threshing belts - not just the belt that looks worn.

On wheeled machines, engage 4WD and lock the differential before the slope, not halfway up it. On tracked machines, confirm that neither steering clutch is slipping and that left and right track tension match.

Throttle timing matters on mechanically governed engines. Give fuel before the bank, not after the rpm has already dropped. Travel resistance, header load and drum load stack on the same engine, so shedding load early works better than adding fuel late.

5. The field itself: ridge height, ditch width, gradient

Ground clearance sets the limit. Mainstream full-feed tracked machines sit at 300-400 mm, while field ridges stand 250-350 mm above the surface, with soft soil on top and a header reaching forward. Geometrically you are already hung up, and horsepower has nothing to do with it.

Gradients are usually classed in three bands: up to 3 degrees is flat, 3-12 degrees is gentle, 12-25 degrees is steep, and above 25 degrees a conventional machine should not be in the field at all. Cross-slope is far more dangerous than fore-and-aft, so keep working cross-slope under 8-10 degrees and do not turn on it.

One number gets misused constantly: a parking requirement is not a climbing ability. JB/T 5117 requires a wheeled combine to hold on a 20 percent (about 11 degrees) firm longitudinal slope, and a tracked machine on 25 percent (about 14 degrees). That is the braking floor - the slope it can stand on, not the slope it can work on.

The rest is geometry: the step between upper and lower fields, ditch width, the angle between ridge top and chassis, the drop from the field road down to the surface. A step over 40 cm will ground the chassis if you drive straight off it, and the header, feed housing and undercarriage all pay for it.

6. Six habits that make it worse

Driving straight into a hard ridge at speed. Travel power against a fixed obstacle damages the header, the front axle and the track. Once is enough.

Turning on the slope. The most common rollover trigger there is. Go straight on the bank, turn on the flat.

Stopping and restarting mid-slope. Peak torque at start-up is precisely when the track lets go.

A full tank, full throttle and the header down, all at once. Three loads, one slope.

Coasting downhill in neutral. Never. Use a low travel gear and let the engine brake.

Crossing a ridge at the wrong angle. Approach at 30-45 degrees, one track first, low gear, steady, no pause in the middle. If the ridge is too high, cut a gap and ramp it with packed soil instead of forcing it.

7. Already stuck or hung up? Work through this order

Stop. Repeating full throttle in one spot digs a crater and sinks you deeper. Neutral, throttle back, get off and look at the ground and the tracks.

Take weight off. Unload grain, lift the header, disengage the header drive. A tonne less changes the odds completely.

Back out. Reverse onto firm ground and pick a new angle. Do not steer left and right in place; the track just walks itself into a worse position.

Build a surface. Straw bales, planks, traction mats, old track pads - anything, but at least 1.5 times the track contact length, with the far end resting on firm ground so the track has something to climb onto.

Then drive out. Low gear, straight line, gentle throttle, with someone spotting from the side. Nobody stands between the rope and the machine.

Tow properly. Two machines, same direction, low speed, no one on the wire, and use the factory tow points - never the header.

Inspect afterwards. Track tension, sprocket teeth, oil temperature, header alignment. Bearings and seals that went under muddy water need flushing and fresh grease.

Table 2  Symptoms and corrective actions

Three sinkings in one field in one season is not an operator problem. It is a field or a machine-matching problem, and the next section is for that.

8. Keep the problem out of the season

Walk the field before you work it. One lap along the edges and through the middle, marking soft spots, deep ditches, high ridges and steps, and fixing the entry and exit routes. Ten minutes on foot saves half a day of recovery.

Drain the paddy ahead of harvest. Three to five days of drainage firms the surface more than any anti-slip measure; clay needs an extra day or two.

Open a working lane first. Cut a 3-4 m strip along the edge before working the block, and ramp the corners and ridges in advance so the machine is never fighting out of a dead corner.

Lower the ridges you have to cross. Take them down below 15-20 cm and compact the top, or build a temporary ramp at least 0.5 m wider than the machine, filled and compacted in layers, under about 15 degrees.

Three maintenance habits. Track tension every shift; hydraulic oil and filters on schedule, not “when it looks dirty”; cooler fins blown clean every shift. All three cost less than one recovery.

Match the machine to the ground. Above 12 degrees with fragmented plots, go tracked and narrow - a body around 1.15 m clears the usual 0.8-1.2 m ridge. In deep mud, read ground pressure rather than horsepower, and stay near or under 0.035 MPa. Above 25 degrees, only a purpose-built hydraulic-levelling machine belongs there; a conventional one is gambling.

Table 3  Gradient classes and machine matching

9. Questions we get asked

What should I check first when a tracked harvester slips on a slope? Three things: track tension, how far the cleats and sprocket teeth have worn, and whether the field surface is too wet. Those account for most slipping, and only after ruling them out should you look at hydraulics and belts.

How high a ridge can a harvester cross? There is no single number. Ground clearance, ridge height above field level, and header height at full lift decide it. In practice, ridges under 15-20 cm with a compacted top can be crossed at an angle; above 30 cm, cut a gap or build a ramp.

How long after rain can I go back into the field? Judge the soil, not the clock. If a handful holds a ball that survives a drop, wait. If the track leaves ruts deeper than about 5 cm, it is still too early. Sandy loam usually needs a day; clay two or three.

Does adding ballast help climbing? On firm ground, yes. In deep mud, no - extra weight raises ground pressure and sinks you faster. There the answer is less weight and more contact area, not more kilos.

Can I work across a slope? Up to 8-10 degrees of cross-slope, at low speed and in a straight line. Beyond that, work up and down the slope and do not turn or change direction on the bank.

A last note

Climbing a bank or crossing a ridge is rarely one cause. Machine, field and operator each take a share. Identify which of the four failures you have, then work through traction, balance, transmission and geometry - most cases are settled at the headland, without a trip to the workshop.

If you are choosing a machine, the gradient, mud depth and ridge width classes in our terrain-selection guide are a reasonable place to start; get the match right and most of what is described here never comes up.

Golddafeng has exported rice harvesters, tractors and implements for years. Across harvest seasons in Southeast Asia, South Asia and Africa, this is the field question we are asked most often - which is why the recovery order above is written as a checklist rather than a paragraph.