Forestry

Bore 20–1000 mm, working pressure up to 500 bar, stroke 6 000 mm and beyond, operating temperature from -50 °C to +200 °C; double-acting, single-acting and telescopic designs. For a harvester crane cylinder we make the rod in C45 or 42CrMo4, induction harden it, plate it with 25–50 µm of hard chrome (60–80 µm for heavy lifting duty) and grind it after plating to Ra ≤ 0.2 µm. Where the rod eye takes side load all day we forge the clevis from the same bar as the rod, which leaves no weld at the eye. A double-lip wiper keeps resin and grit out of the gland, and position or pressure sensors can be built in. Every cylinder is pressure tested at 1.5× working pressure for at least five minutes.

Typical parts

• Crane lift, slew and extension cylinders for harvesters and forwarders
• Grapple and rotator cylinders for log loaders
• Felling head clamp, tilt and saw feed cylinders
• Stabiliser cylinders for forwarders and loaders

Gear, planetary, axial-piston and radial-piston motors with displacement from 0.25 to 8000 cc/rev, working pressure up to 450 bar, speed from 0.5 to 12000 rpm and operating temperature from -40 °C to +120 °C. Radial-piston motors give high torque at low speed, which is what a feed roller needs to pull a stem through the head and what a winch needs on a slope. Mounting flanges follow SAE and DIN and the dimensions match the common equipment platforms, so our motor fits the original mount. Before dispatch each unit goes through a functional test and a pressure test. Motors that are already in service can be sent in for refurbishment.

Typical applications

• Radial-piston motors for feed rollers and winches
• Saw motors for harvester and processing heads
• Track drive motors for tracked harvesters and feller bunchers
• Slew motors for loader cranes

Rotators, slew rings and travel reducers on a forestry machine run in mud and dust and see high torque in short bursts. We cut and grind gears up to 2000 mm to ISO 1328; grade 7 is the usual requirement for a loaded reducer stage. Gears are carburised to a case depth of 1 to 3 mm at 56–62 HRC over a core of 240–300 HB. A pinion shaft comes out of one billet, so there is no keyed joint that can work loose. Shafts, pins and bushings hold ±0.05 mm and IT6–IT7 fits; our lathes take parts up to 2 m in diameter and 16 m long. If all you have is a worn wheel, we measure it and make the replacement from that.

Typical parts

• Rotator gears, slew rings and pinions for crane bases
• Travel reducer and bogie drive gears, splined shafts, sprockets
• Boom and head pins, hardened bushings
• Cylinder bodies, glands and rod ends

Valve blocks, sensor housings and control units sit on the crane, on the head and in the cab, and anything mounted on the boom has to be light. We cast them in aluminium to ±0.1–0.3 mm with Ra 1.6–6.3 µm, which leaves most surfaces without machining, and wall thickness can go down to 0.5–1.5 mm. T6 heat treatment, anodising and powder coating are available. Castings that carry pressure are X-rayed for porosity.

Typical applications

• Valve and manifold housings for head and crane control
• Sensor and controller enclosures on the boom and in the cab
• Brackets, covers and pump housings

Control blocks, joysticks and small drives on a forestry machine use gears, levers and pistons in quantities where it is cheaper to sinter them than to cut each one from bar, and sintering saves up to 30% of the material as well. Compaction pressure goes up to 800 MPa and density to 97%. Tolerance is ±0.05 mm as sintered and ±0.02 mm for MIM parts. Every lot is checked for density, hardness and dimensions.

Typical applications

• Sintered gears and sprockets for pump and reducer drives
• Small pistons, levers and latches for control blocks
• MIM parts for valves and couplings

A mulcher tooth hits wood, stones and soil in the same revolution, so fracture toughness matters more for it than hardness. For that duty we use a coarser-grained grade with more cobalt, such as K40 with 12–16% cobalt. Where the wear is abrasion without shock, on a debarker tip or a wear plate for example, a fine-grained low-cobalt grade keeps its edge longer. We sinter tungsten carbide (WC-Co) in-house at 1 350–1 500 °C to 1 400–2 000 HV, grade it to ISO 513 and diamond grind it to ±0.01 mm. Parts range from 0.001 to 300 kg and from Ø 3 to 500 mm. The braze alloy and the press-fit interference are specified together with the insert, since the joint usually fails before the carbide does.

Typical applications

• Carbide teeth and tips for mulcher rotors and stump cutter wheels
• Knife inserts for chippers and debarker tips
• Wear plates and tiles for heads and feed channels
• Guide bushings and sleeves for hydraulic equipment