Poclain MS / MSE Motor Rebuild Guide: Teardown, Brake, Seal Kits and Torque

To rebuild a Poclain MS or MSE radial piston motor, pull the motor and drain the case, release and strip the brake (if fitted), lift off the bearing support, then remove the cam ring, cylinder block and valving, replace every seal with the kit for your frame size and speed type, and reassemble to the torque and shim values in Poclain's repair manual. Before start-up the case must be filled with clean oil through the highest bleed screw, which Poclain calls mandatory.

The procedure below follows Poclain's own repair manuals, not a forum thread or a pirated PDF. Poclain wrote them for machine builders and repair shops, and they assume a press, the right mandrels and a clean bench. If you have those, an MS motor is a very serviceable unit. If you do not, the brake spring washer and the bearing preload are where home rebuilds go wrong.

What do you need before you open a Poclain MS motor?

Start with the identification plate. It carries three things: the model code (for example MS05-0-133-F05-1320-0000), the part number and the serial number. Poclain says the part number and serial number must both be quoted to order spare parts. Since October 2003 Poclain part numbers have seven characters in the form A00000X, and the plate layout changed in January 2005, so an older motor will look different from a newer one. If you are not sure what you have, our guide to identifying a Poclain MS motor walks through the code.

Tooling, from the manual's tool lists:

• A hydraulic press with enough capacity for the brake and bearing forces (the force tables run past 200,000 N on the larger frames).
• Torque wrenches covering 6-30 N·m, 50-240 N·m and 160-800 N·m.
• Internal snap ring pliers for rings of 85 to 200 mm diameter, and external pliers for the bearing snap ring.
• Loctite 7471 activator, Loctite 638 and Loctite 542, isopropyl alcohol, anti-oxidizing grease (Poclain names AGIP Autotop 2000 or Mobil XHP 222) and LG EP2 grease for the bearings.
• Poclain's mandrels for the brake spring washer, brake cover and bearing races, or an M12 or M16 class 12.9 bolt (fully threaded, 150 mm long) with a mandrel to compress the brake spring. The bolt size goes by brake: M12 for F02 through F07 brakes, M16 for F08 through F19.

The 2012 manual adds a rule worth repeating: no wood. No wooden mallets, blocks or bench tops. Use nylon or plastic mallets and keep the bench clean, because the valving and cam faces do not forgive grit.

How do you troubleshoot a Poclain MS motor before tearing it down?

Poclain's troubleshooting chart is short, and half of it points outside the motor. Work through it before you pull anything.

Symptom	Likely cause (per Poclain)	What to do
Steady rumble with no load	Worn bearing support	Replace the bearing support
Vibration with no load	Loose mounting bolts or piping	Retighten to torque
Clattering under load	Boost pressure too low	Check the setting and condition of the counter-pressure valve
Noisy under load	Cavitation, or excessive internal leakage	Replace the cylinder block and distribution (valving) assembly
Motor will not turn	No supply, circuit not reaching pressure, internal leakage, or brake staying on	Check pump drive and inlet, the relief valve, the block and valving, and the brake pilot circuit
Slow under load	Low pump flow, internal leakage, or low working pressure	Check pump speed and condition, the block and valving, and the relief setting
Runs irregularly	Irregular flow or excessive leakage	Check pump flow, then the block and valving
External leaks	Case pressure too high, damaged seals, or bad assembly	Check the drain line and filter, replace seals, check screw, bleed screw and fitting torque

The case pressure line is the one people skip. A restricted or undersized drain will blow seals on a perfectly good motor, and a new seal kit will not fix it. Poclain's chart also notes the chain it sees in the field: damage, then metal particles, then the filters catching them. Cut the filter open before you order parts. For the general method, see our hydraulic motor repair and rebuild guide and the case drain flow test.

How do you release the brake on a Poclain MS motor?

Motors with the multi-disc parking brake are spring applied and pressure released. To turn the shaft on the bench, or to free a machine, Poclain gives a mechanical release (except on DYNA+ bearing supports): pull and discard the plug (142) in the brake cover, run a bolt into the brake piston, then tighten the nut until the shaft turns freely. Fit a new plug afterward. The force and equivalent nut torque depend on the brake size in the model code:

Brake	Release force	Equivalent nut torque	Nut
F02-F04	18,000 N (4,000 lbf)	42 N·m (30.9 lbf·ft)	M12
F05-F07	20,000 N (4,500 lbf)	47 N·m (34.6 lbf·ft)	M12
F08	34,000 N (7,600 lbf)	110 N·m (81.1 lbf·ft)	M16
F11, F12, F19	45,000 N (10,000 lbf)	140 N·m (103 lbf·ft)	M16

Source: MS02-MS18 repair manual, page 9.

DYNA+ bearing support motors are released hydraulically instead. Poclain's method: remove the irrigation valve, fit the M18x1.5 plug assembly (part number 003037414M), and feed the brake release ports from a hand pump with a reservoir of at least 0.5 L, a check valve, a relief valve set no higher than 30 bar (435 psi), a dump valve and a 0-100 bar gauge. Opening the dump valve re-applies the brake. Refit the irrigation valves when you are done.

To check a brake after repair, Poclain's test is simple: with zero brake pressure, bleed the brake at the highest screw (112), pressurize the motor to the relief setting, and the shaft must not turn. If it turns, the brake needs replacing. Brake pilot pressure is a minimum of 12 bar (174 psi) and a maximum of 30 bar (435 psi). Do not try to "run in" a multi-disc brake.

What order do you take a Poclain MS motor apart?

1. Remove the motor. Release supply pressure, disconnect the drain line at the tank end so the tank does not siphon, plug every hose, unplug the speed sensor, remove the mounting bolts and lift the motor out. Drain the case.
2. Stand it on the bearing support with nuts run onto the studs to protect the threads.
3. Strip the brake (brake motors only). The brake cover (141) is destroyed coming off, so have a new one on hand. Remove the cover and its O-ring (143), compress the spring washer (108) with the bolt method or a press, mark which way the snap ring (109) faces, remove it, then the spring washer and brake piston (107) and its O-ring (106). Remove and discard the brake housing screws (102), lift the brake housing (101) and take out the shims (105) and discs (103, 104). On two-speed motors, pull the displacement change spool (053) and discard O-rings 045 and 057.
4. Mark the cam position against the valving cover, remove the bearing support screws (042) and lift the bearing support off with a hoist.
5. Remove the cam ring (026) and discard its two O-rings (027), one on the valving cover side and one on the bearing support side.
6. Lift out the cylinder block assembly (010). Small blocks come out by hand; the 2012 manual shows two screwdrivers or lifting lugs and a jib on the big ones.
7. Remove the valving (047) from the valving cover (041) by levering at the indexing pins or flange. On two-speed motors, mark its position against the cover first. Take out the springs (052) and discard the seals and back-up rings (048). Keep the valving covered; dust on that face is a leak later.
8. Strip the bearing support only if you have to. Pressing the shaft out destroys the inner bearing race, and the lip seal and bearing cage are cut out with a chisel. That is a press job with Poclain's force tables, covered on pages 29 to 45 of the manual.

What should you inspect, and what always gets replaced?

Poclain publishes procedures and replacement rules for the MS, not a list of wear limits for the cam, pistons or valving. So the inspection is visual and by feel, and the replacement rules carry the weight:

• All O-rings, seals and back-up rings are replaced. Poclain says to fit new ones every time and grease them before assembly.
• Piston clips, lunambulles and spacers are replaced every time the clips come off (2012 manual).
• Do not replace individual piston parts. Poclain recommends against swapping rollers or bushings on their own, and after 100 hours of running it recommends replacing the complete cylinder block sub-assembly, or all the piston assemblies at once.
• Radial clips must sit with less than 0.2 mm (0.008 in) gap to the block outside diameter, must go in with the special tool for that motor, and cannot be repositioned. A clip that does not lock is scrapped.
• Brake housing and valving cover mating faces on the glued (type 1) brake: scrape off old glue with a blade, but never file or sand the face. Poclain wants the original finish kept.
• Shaft seal surfaces and splines on the shaft, and the seal seat in the bearing support, get checked before any new seal goes in.
• Rust, mud and water are removed from every groove and face before reassembly.

Our shop view: a cam ring with spalling on the lobes, or a valving face that is scored, is a parts decision, not a seal kit job. Look hard at both before you buy a kit.

Which seal kit fits my Poclain MS or MSE motor?

The kit goes by frame size and by speed type. A single-speed (1C) motor has a plain valving; a two-speed (2C) motor has the displacement change spool and extra seals in the valving cover, so it takes a different kit. The model code tells you which you have.

Frame	Single-speed kit	Double-speed kit	Frame parts and genuine Poclain kits
MS02	MS02-1S	MS02-2S	MS02 parts and genuine kits
MSE02	MSE02-1S	MSE02-2S	MSE02 parts and genuine kits
MS05	MS05-1S	MS05-2S	MS05 parts and genuine kits
MSE05	MSE05-1S	MSE05-2S	MSE05 parts and genuine kits
MS08	MS08-1S	MS08-2S	MS08 parts and genuine kits
MSE08	MSE08-1S	MSE08-2S	MSE08 parts and genuine kits
MS11	MS11-1S	MS11-2S	MS11 parts and genuine kits
MS18	MS18-1S	MS18-2S	MS18 parts and genuine kits
MSE18	MSE18-1S	MSE18-2S	MSE18 parts and genuine kits

The brake has its own seals. Poclain notes that a brake repair kit can contain two piston O-rings of different diameters: measure the groove diameter on the brake piston and fit the matching one. Genuine Poclain kits, shaft seals, bearings and shim kits are listed by frame in the collections above and in our Poclain parts catalog. Our MS seal kit guide covers single versus double speed in more detail. Send us the plate details and we confirm the kit before it ships; we do not promise a fit off a frame size alone, because OEM specials exist.

How do you put it back together?

Valving

Fit new O-rings lubricated with petroleum jelly, then the back-up rings. The 2012 manual warms the back-up rings first: 5 minutes at 80-90°C in an oven, or in a sealed bag in hot water, and fit them while warm. Run a finger around each one to make sure it is not twisted. Put the springs in their holes with petroleum jelly, oil the valving, and press it into the cover until the timing pins engage. Do not force it.

Orientation matters on two-speed motors. A single-speed valving has no particular direction. On a two-speed valving marked with letters, the 2012 manual sets it by the third block of the model code: with D, E, F or L, the letter R on the valving faces the displacement spool port; with G, H, J or M, the letter L faces it. With A, B or C there, the valving simply goes in until its timing pin engages. If there is no letter on the valving, go by the marks you made at teardown.

Cam ring and cylinder block

Grease the new cam O-rings, except on motors with an Autolock groove, where Poclain says never to lubricate them. Fit a new O-ring (027) and the cylinder block assembly, then the cam with its timing hole (or, without a timing hole, its chamfers) toward the bearing support. On two-speed motors where the displacement ratio is not 2, the cam has unequal lobes marked P and M, and the letter must face the two-speed spool. Poclain's example is an MS18 at 1747-1049-698 cc: P is the small 698 cc displacement and M the medium 1049 cc. Center the cam with two opposite screws, fit the bearing support with the hoist, and torque the screws (042). On shaft motors, the ports must sit perpendicular to the motor mounting axis.

Bearing support preload

This is the step that decides bearing life. Poclain presses the bearing to a set force F for the frame, backs off to 20,000 N (4,500 lbf), turns the support at least five turns each way to seat the rollers, presses again, measures the gap between the thrust ring and the snap ring, and picks shims to hit a rolling torque C from the table on page 75. The thickest shim goes toward the bearing, and the thrust ring must not turn by hand once the snap ring is in. Without a press and the table, do not guess this one.

Brake

Oil the new discs with hydraulic fluid and stack them starting and finishing with an outer disc (103), alternating with inner discs (104). Pressurize the brake, measure piston stroke with a dial indicator, and shim to the stroke in the brake table, thickest shim toward the piston and as few 0.2 mm shims as possible. On the glued brake housing: degrease both faces with isopropyl alcohol, brush Loctite 7471 activator on the valving cover face and wait 2 minutes, lay a continuous 5-10 mm bead of Loctite 638 on the brake housing along the bolt circle, and assemble with new class 12.9 screws within 10 minutes. Then leave it alone for six hours: no shocks, and no use or testing of the brake or motor. Finish with a new O-ring, a new brake cover snapped into its groove with the mandrel, and a new plug.

What are the torque values for a Poclain MS02-MS18 motor?

Fastener	Torque
Bearing support screws (042), MS02, MS05, MS08	145 ± 14 N·m (107 ± 10 lbf·ft)
Bearing support screws (042), MS11, MS18	355 ± 35 N·m (262 ± 26 lbf·ft)
DYNA+ bearing support	355 ± 35 N·m (262 ± 26 lbf·ft)
End cover, DYNA+ bearing support	49 ± 5 N·m (36 ± 4 lbf·ft)
End cover screws (066), MS02 and MS05 without brake	49 ± 5 N·m (36 ± 4 lbf·ft)
End cover screws (066), MS08 without brake	86 ± 9 N·m (63.4 ± 6 lbf·ft)
End cover screws (066), MS11 and MS18 without brake	210 ± 21 N·m (155 ± 15 lbf·ft)
End cover, MSE18 two-speed symmetric: screws 066 / screws 135	210 ± 21 N·m (155 ± 15 lbf·ft) / 86 ± 8.6 N·m (63.43 ± 6.34 lbf·ft)
Brake housing to valving cover screws (102), MS02 and MS05	85 +0/-16 N·m (63 +0/-12 lbf·ft)
Brake housing to valving cover screws (102), MS08	145 +0/-30 N·m (107 +0/-22 lbf·ft)
Brake housing to valving cover screws (102), MS11 and MS18	355 +0/-70 N·m (262 +0/-52 lbf·ft)
Speed sensor screw (165)	35 ± 3.5 N·m (26 ± 2.6 lbf·ft)
Valving cover bleed screws (2012 manual)	8 ± 1 N·m (5.9 ± 0.73 lbf·ft)

Source: MS02-MS18 repair manual, tightening torque summary (pages 75-76 of the hosted PDF); bleed screws from the 2012 MS manual, page 114. Anything not listed takes Poclain's standard torque for the screw size and grade, with threads oiled unless the screw is glued or pre-coated:

Size	Grade 8.8	Grade 10.9	Grade 12.9
M6	10 N·m (7.5 lbf·ft)	14 N·m (10 lbf·ft)	17 N·m (12.5 lbf·ft)
M8	25 N·m (18.4 lbf·ft)	35 N·m (26 lbf·ft)	41 N·m (30 lbf·ft)
M10	49 N·m (36 lbf·ft)	69 N·m (51 lbf·ft)	83 N·m (61 lbf·ft)
M12	86 N·m (63.4 lbf·ft)	120 N·m (88.4 lbf·ft)	145 N·m (107 lbf·ft)
M14	135 N·m (100 lbf·ft)	190 N·m (140 lbf·ft)	230 N·m (170 lbf·ft)
M16	210 N·m (155 lbf·ft)	295 N·m (218 lbf·ft)	355 N·m (262 lbf·ft)
M18	290 N·m (214 lbf·ft)	405 N·m (299 lbf·ft)	485 N·m (358 lbf·ft)
M20	410 N·m (302 lbf·ft)	580 N·m (428 lbf·ft)	690 N·m (509 lbf·ft)

Standard torques ± 10%, per DIN 912, from the repair manual and the 2012 MS manual page 193.

How do you start up a rebuilt Poclain motor?

1. Flush the circuit before the motor goes back on line. Poclain wants a temporary bypass around each motor during flushing, and on a closed loop a 10 micron absolute filter without bypass on the return branch.
2. Fill the case. Loosen the highest bleed screw, fill with new oil, and retighten when oil comes out (the installation guide gives 5 N·m for this step). Poclain calls this mandatory before start-up. Running a radial piston motor with a dry case is the fastest way to waste a rebuild.
3. Bleed the brake at its bleed screw until fluid runs out, then retighten.
4. Check pilot pressures. Brake release and two-speed selection both want 12 bar minimum and 30 bar maximum. Poclain says not to put a check valve or poppet valve in those pilot lines between the charge pump and the pilot valve.
5. Check rotation. On the bench Poclain supplies 80 bar (1,160 psi) at 50°C (122°F). For single-speed motors and those with G, H or J in the model code, pressure at port L turns the shaft clockwise; with D, E or F in the code, port L turns it counterclockwise.
6. Keep the oil clean and in range. Poclain specifies ISO 4406 18/16/13 for industrial circuits and 20/18/15 or better for closed loops, viscosity always between 9 and 500 cSt, and motor temperature between 0 and 80°C (32-176°F) in operation. Our cleanliness and flushing guide explains the codes.

For industrial drives that cannot be brought up gradually, the installation guide gives a run-in: large displacement, brake fully released, 5 minutes at 100 bar supply with 80 bar return, then 30 minutes at 200 bar supply with 180 bar return, in both directions, at 20-50% of catalog maximum speed, with the cam periphery not exceeding 90°C (194°F). See our start-up procedure guide for the pump side of the system.

Should you rebuild it yourself or have it rebuilt?

A seal kit job on a single-speed MS02 or MS05 with no brake is realistic for a shop with a press and a torque wrench. A brake motor, a two-speed motor, or anything that needs bearings is a different job: glued brake housings, preload shimming to a rolling torque, radial clip tooling and valving orientation all have to be right the first time. If the cam or valving is damaged, you are buying major parts either way, and that is when it pays to have the motor torn down and quoted before you spend money.

Frequently asked questions

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