Service Manual

Axial Piston Motors
MP1

www.danfoss.com

Service Manual
MP1 Motor

Revision history

2 | © Danfoss | April 2023

Table of revisions
Date

ChangedRev

April 2023

Various modifications

0203

March 2023

Fixed notation of 28/32 port size on pressure measuremnts

0202

October 2022

Added size 28/32

0201

November 2020

Updated Part Option for Speed and Temperature Sensor

0104

March 2020

Changed number of the shuttle shifts to 4 bar

0103

December 2019

Changed torque units from N•m [lbf•ft] to N•m [lbf•in]0102

December 2019

First edition

0101

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Contents
Introduction
Hydrostatics Servicing Overview................................................................................................................................................ 5
Safety Precautions............................................................................................................................................................................5
Unintended machine movement..........................................................................................................................................5
Flammable cleaning solvents................................................................................................................................................. 5
Fluid Under Pressure..................................................................................................................................................................5
Personal safety............................................................................................................................................................................. 5
General Information
MP1 Motors Overview.....................................................................................................................................................................6
MP1 Motor Features........................................................................................................................................................................ 6
System Diagram................................................................................................................................................................................7
Schematic Diagram..........................................................................................................................................................................8
Technical Specifications
Design Specifications......................................................................................................................................................................9Technical Data................................................................................................................................................................................... 9Operating Parameters.....................................................................................................................................................................9
Fluid Specifications....................................................................................................................................................................... 10
System Design Parameters
Determination of Nominal Motor Size................................................................................................................................... 11
Variables.......................................................................................................................................................................................11
Part Options
Shaft Options...................................................................................................................................................................................12
Loop Flushing Valve......................................................................................................................................................................12Anti-Cavitation and Shock Valve.............................................................................................................................................. 13
Speed and Temperature Sensor............................................................................................................................................... 15
Available Sensors......................................................................................................................................................................15
Sensor Position.......................................................................................................................................................................... 16
Speed Sensor 4.5 - 8 V.............................................................................................................................................................16
Speed Sensor 7 - 32 V..............................................................................................................................................................17
Output Pulses.............................................................................................................................................................................17
Operating Parameters
Overview........................................................................................................................................................................................... 18
Speed Ratings..................................................................................................................................................................................18
System pressure............................................................................................................................................................................. 18
Case Pressure...................................................................................................................................................................................19
Temperature.................................................................................................................................................................................... 19
Viscosity.............................................................................................................................................................................................19
Pressure Measurements
MP1M20/24 SAE A Flange Port Locations and Specifications....................................................................................... 20
MP1M20/24 SAE B Flange Port Locations and Specifications....................................................................................... 21
MP1M20/24 Cartridge Flange Port Locations and Specifications................................................................................22
MP1M28/32 SAE B Flange Port Locations and Specifications....................................................................................... 23
MP1M28/32 Cartridge Flange Port Locations and Specifications................................................................................24
Fluid and Filter Maintenance
Recommendations of Fluid and Filter Maintenance.........................................................................................................25
Initial Start-Up ProceduresStart-up Safety Precautions........................................................................................................................................................26
Inspect the Unit.............................................................................................................................................................................. 26
Fill System Components with Hydraulic Fluid.....................................................................................................................26
Install Charge Pressure Gauge...................................................................................................................................................27
Calibrate the Motor/Transmission........................................................................................................................................... 27
Troubleshooting
Troubleshooting Overview.........................................................................................................................................................28
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Contents
System Noise or Vibration...........................................................................................................................................................28
Minor Repair
Shaft Seal and Dust Seal.............................................................................................................................................................. 29
Shaft seal and dust seal removal.........................................................................................................................................29
Shaft Seal and Dust Seal Assembly.................................................................................................................................... 30
Speed Sensor................................................................................................................................................................................... 31
Speed Sensor Removal........................................................................................................................................................... 31
Speed Sensor Assembly......................................................................................................................................................... 31
Loop Flushing Valve......................................................................................................................................................................32
Loop Flushing Valve Removal..............................................................................................................................................32
Inspect the Components....................................................................................................................................................... 32
Install the Loop Flushing Valve............................................................................................................................................32
Anti-cavitation Valve.....................................................................................................................................................................33
Remove the Anti-cavitation Valve (Supply Check Relief Valve)...............................................................................33
Inspect the Components....................................................................................................................................................... 33
Install the Anti-cavitation Valve...........................................................................................................................................33
Torque Chart
Fasteners and Torque...................................................................................................................................................................34

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Introduction
Hydrostatics Servicing Overview
This manual includes information on installation, maintenance, and minor repair of the MP1 motor. It
includes a description of the unit and its individual components, troubleshooting information, and minor
repair procedures.
Performing minor repairs may require the unit to be removed from the vehicle/machine. Thoroughly
clean the unit before beginning maintenance or repair activities. Since dirt and contamination are thegreatest enemies of any type of hydraulic equipment, follow cleanliness requirements strictly. This isespecially important when changing the system filter and when removing hoses or plumbing.
A worldwide network of Danfoss Global Service Partners is available for major repairs. Danfoss trains andcertifies Global Service Partners on a regular basis. You can locate your nearest Global Service Partner
using the distributor locator at http://www.danfoss.com.
For detailed technical information about the MP1 motor, please see the relevant technical information
document.
Attention
Major repairs requiring the removal of a unit’s center section, servo sleeves, or front flange voids thewarranty unless a Danfoss Authorized Service Center performs them.
Safety Precautions
Always consider safety precautions before beginning a service procedure. Protect yourself and othersfrom injury. Take the following general precautions whenever servicing a hydraulic system.
Unintended machine movement
Unintended movement of the machine or mechanism may cause injury to the technician or bystanders.
Secure the machine or disable/disconnect the mechanism while servicing to protect against unintended
movement.
Flammable cleaning solvents
Some cleaning solvents are flammable.
Do not use cleaning solvents in an area where a source of ignition may be present to avoid possible fire.
Fluid Under Pressure
Escaping hydraulic fluid under pressure can have sufficient force to penetrate your skin causing serious
injury and/or infection. This fluid may also be hot enough to cause burns.
Relieve pressure in the system before removing hoses, fittings, gauges, or components. Never use yourhand or any other body part to check for leaks in a pressurized line. Use caution when dealing withhydraulic fluid under pressure. Seek medical attention immediately if you are cut by hydraulic fluid.
Personal safety
Protect yourself from injury whenever servicing a hydraulic system.
Use proper safety equipment, including safety glasses, at all times.
Hazardous material
Hydraulic fluid contains hazardous material.
Avoid prolonged contact with hydraulic fluid. Always dispose of used hydraulic fluid according to state,
and federal environmental regulations.

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MP1 Motor
General Information
MP1 Motors Overview
The MP1 motor is a fixed displacement axial piston motor intended for closed and open circuit medium
power applications. These motors are designed primarily to be combined with other products in closed
and open circuit systems to transfer and control hydraulic power.
The MP1 motor consists of four rotating groups (displacements) and three housing (mounting)configurations. An SAE-A two bolt, SAE-B two-bolt and a cartridge style (for space optimized gear box
mounting ) configurations.
The motor is ideally configured for installations requiring compact packaging and optimized plumbing
such as wheel ends. The standard porting configuration is twin radial (side) O-ring boss main ports.
MP1 Motor Features

•
•
•
•
•
•

Four displacements allow the optimum selection of hydraulic motor for the lowest possible installed
cost
SAE-A & B, two bolt, and cartridge style mounting configurations available
Metric and inch O-ring boss system port interfaces
Short and compact; fits into existing installation with improved porting
Proven reliability and performance
Worldwide sales and service

Expanded functionality

•
•
•
•
•

6 | © Danfoss | April 2023

Open circuit Fan Drive application
PLUS+1® Compliant speed sensor option
Integrated Flushing valve option available
Anti-cavitation valve option available
Shock valve option available

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General Information
System Diagram
Pictorial system diagram

Heat exchanger
bypassReservoir

FilterHeat
exchanger

Variable
Displacement
Pump

MP1
Axial piston
Motor

Charge pressure
relief valve

Chargepump

Loop flushing valve

High pressure
relief/check valves

Suction flow

Working Loop (Low Pressure) and Charge Pressure

Case flow

Working Loop (High Pressure)P400619

The system diagram above shows the MP1 motor in a simple closed-loop hydrostatic propel application.
The motor is driven by a variable displacement pump. The motor shows an integral loop flushing optionthat will remove heat and contaminants from the system loop.

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MP1 Motor
General Information
Schematic Diagram
Closed Circuit
L2

N

A

B
L1
P400620

For a close loop system, the system ports (A and B) connect to the high pressure work lines. The motor
receives pressurized fluid in its inlet port and discharges de-energized fluid through the outlet port.
Either port can act as inlet or outlet; flow is bidirectional. The motor has two case drains (L1 and L2). The
motor may include loop flushing. Loop flushing provides additional cooling and filtration capacity.
Open Circuit
L2

N

A

CCW

B
L1
P400648

An open circuit configuration is also possible for the motor and such a system is shown above. A shock
valve and an anti-cavitation valve is provided to protect the unit from sudden pressure surges as well as
cavitation. The flow path of pressurized fluid is from port A through port B. In this configuration, thedirection of rotation of the motor is counter clockwise as seen from shaft side. Similarly, if the anticavitation and shock valve is oriented in the reverse position, the direction of rotation will be clockwise.
Thus, pressurized fluid flow path is from port B through port A.

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Technical Specifications
Design Specifications
Features

MP1 Motors

DesignAxial piston motor with fixed displacement design.

Direction of output rotation (as seen from shaft side)

Clockwise or counterclockwise

Recommended installation position

Motor installation position is discretionary, The housing must always be filled withhydraulic fluid. Consult Danfoss for non-conformance to these guidelines.

Technical Data
FeatureUnit

MP1M20Model configuration
Displacement

MP1M24

MP1M28

MP1M3228.0 [1.71]

31.8 [1.94]

Fixed displacement motor
cm3/rev [in3/rev]

20.0 [1.22]

24.0 [1.46]

Mass moment of inertiakg•m2 [slug•ft2]
of rotating components

0.0010 [0.0007]

0.0016 [0.0011]

Mass (Weight) dry

5.6 [12]8.0 [17.6]

ISO 3019-1 flange 82-2 (SAE-A), 2 bolt
ISO 3019-1 flange 101-2 (SAE-B), 2 bolt
Cartridge mounting style

ISO 3019-1 flange 101-2 (SAE-B), 2 bolt
Cartridge mounting style

Spline 13T 16/32
Spline 15T 16/32
Spline 17T 24/48

Spline 13T 16/32
Spline 15T 16/32

kg [lb]Mounting flange

Output shaft options

Straight keyed 22.2 dia.
Tapered 22.2 dia. 1:8
System port configuration A, B

ISO 11926-1, 7/8-14 (SAE O-ring boss)

ISO 11926-1, 1-1/16-12 (SAE O-ring boss)

ISO 6149-1, M22x1.5 (Metric O-ring boss)

ISO 6149-1, M27x2 (Metric O-ring boss)

ISO 11926-1, 3/4-16 (SAE O-ring boss)

Case drain ports L1, L2

ISO 6149-1, M18x1.5 (Metric O-ring boss)

Operating Parameters
20/24

28/32

Rated

4200

3900

Maximum

4700

4400

3400

3100

3800

3500

Parameter

Unit
Closed Circuit 1)

Speed limit
Open Circuit
System pressure

Case pressure

Rated
Maximum

Maximum working pressure2)
Maximum pressure
Rated
Maximummin-1(rpm)bar [psi]bar [psi]

350 [5000]
380 [5429]
2 [29]
6 [87]

1) At the limit speed, system minimum low pressure is 18 bar.
2) Applied pressures above maximum working pressure requires Danfoss application approval.

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MP1 Motor
Technical Specifications
Motor speed limit in relation to output (low) pressure

Output speed n/nmax

1.00

0.95

0.90

0.85

0.80

0

2

4

6

8

10

12

14

16

18

Outlet pressure [bar]P400718

Fluid Specifications
Features

Units
Intermittent1

Viscosity

Temperature range3

Minimum
Recommended range

20/24/28/32
5 [42]

mm2/sec. [SUS]

7 [49]
12 - 80 [66 - 370]

Maximum (cold start)2

1600 [7500]

Minimum (cold start)-40 [-40]

Recommended range
Maximum continuous°C [°F]

Maximum intermittent
Cleanliness per ISO 4406

60 - 85 [140 - 185]
104 [220]
115 [240]
22/18/13 (as per ISO 4406)

1 Intermittent=Short term t <1 min per incident and not exceeding 2 % of duty cycle based load-life.
2 Cold start = Short term t < 3 min, p < 50 bar [725 psi], n < 1000 min-1 (rpm)3 At the hottest point, normally case drain port.

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System Design Parameters
Determination of Nominal Motor Size
The following equations are used to compute the input flow, output torque, output power and speed.
Generally, sizing the right motor starts with an evaluation of the machine requirements such as speed
and torque. Select a motor that will transmit the required torque, then select a pump that will meet theflow and pressure requirements of the motor.
Unit:

Metric System:
Vg • nQe =1000 • η v

Output torqueMe =Output power

Pe =

Speed

n=

Vg • ∆p • η m
20 • πQe • ∆p • η t
600

Qe • 1000 • η v
VgInch SystemVg • n

l/min

Qe =

Nm

Me =

kW

Pe =

min-1

n=

[gpm]

231 • η v
Vg • ∆p • η m[lbf•in]2•πVg • n • ∆ p • η t
396 000
Qe • 231 • η v
Vg

[hp]

(rpm)

Variables

SI units [US units]
Qe = Input flow l/min (US gal/min)
Me = Output torque N•m (lbf•in)
pe = Output power kW (hp)n = Speed min-1 (rpm)Vg = Displacement per revolution cm3/rev [in3/rev]
pO = Outlet pressure bar [psi]pi = Inlet pressure bar [psi]∆p = pO - pi (system pressure) bar [psi]ηv = Volumetric efficiency
ηmh = Mechanical-hydraulic efficiency
ηt = Motor total efficiency (ηv • ηmf)

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MP1 Motor
Part Options
Shaft Options
MP1 motors are available with a variety of splined, straight keyed, and tapered shaft ends. Nominal shaft
sizes and torque ratings for some available shafts are shown in the accompanying table.
Torque ratings assume no external radial loading.Continuous torque ratings for splined shafts are basedon spline tooth wear, and assume the mating spline has a minimum hardness of Rc 55 to full spline depth
and coupling has good lubrication.
Maximum torque ratings are based on shaft torsional strength and assume a maximum of 200,000 load
reversals.
Shaft availability and maximum torque ratings
Shaft optionN•m [lbf•in]Spline, 13 tooth, 16/32 pitch

226 [2000]

Spline, 15 tooth, 16/32 pitch

362 [3200]

Spline, 17 tooth, 24/48 pitch

165 [1460]

Tapered, Ø22.2 mm

362 [3200]

Straight keyed, Ø22.2 mm

226 [2000]

Recommended mating splines for MP1 motor splined output shafts should be in accordance with ANSI
B92.1. Refer to the shaft option drawings for detailed specifications of each spline.

Loop Flushing Valve
Closed circuit systems may require loop flushing to meet temperature and cleanliness requirements. MP1
motors are available with an optional integral loop flushing. A loop flushing valve will remove heat andcontaminants from the main loop at a rate faster than otherwise possible.
The hydraulic circuit of an MP1 motor with loop flushing option is shown below. The MP1 motor loop
flushing design is a simple spring centered shuttle spool with an orifice notch.
L2

N

A

Plug

Spring
Notch

Spool

Spring guide

B
L1
P400637

A loop flush shuttle spool is used to separate system A and system B pressures. System delta pressure willcause the shuttle spool to shift, allowing the low side system pressure to flow to the orifice towards thecase. The shuttle shifts at approximately 4 bar [57 psi]. The flushing flow is a function of the low loop
system pressure and the size of the notch.
Loop flush flow options of 1.5 & 3.6 l/min [0.4 & 1.0 gal/min] are available for the 20/24cc frame size. Loopflush flow options of 5.2 and 8.0 l/min [1.4 & 2.1 gal/min] are available for the 28/32cc frame size. These
options are adequate for most applications.

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Part Options
When a MP1 pump is used with an external loop flushing shuttle valve, ensure that the charge setting of
the pump matches the setting of the loop flushing shuttle valve. Contact your Danfoss representative forthe availability of additional charge relief settings.
Loop flush characteristic curves(Size 20/24) 1.5 L and 3.6 L@15 bar, oil temp=50°C
5
1.5L - 50°C

Flow [L/min]

4

3.6L - 50°C

3

2

1

0

0

5

10
15
System pressure _ low side [dbar]

20

25
P400656(Size 28/32) 5.2 L and 8.0 L@15 bar, oil temp=50°C
10
5.2 L - 50°C

Flow [L/min]

8

8.0 L - 50°C

6

4

2

0

0

5

10
15
System pressure _ low side [dbar]

20

25
P400783

Anti-Cavitation and Shock ValveThe MP1M fixed motors are available with an anti-cavitation valve option. The key application for thisoption is open circuit fan drives.
The anti cavitation valve function as a check valve within the same cavity which is integrated into theendcap. The check valve function provides protection against cavitation that can occur upon
introduction of an overrunning load or due to loss of input flow. In such case, the system delta pressure
becomes negative and the check valve opens connecting the motor inlet and outlet, effectively shortcircuiting the motor. The shock valve function is intended to be used for system overpressure protection
events of limited duration only. It is not intended for continuous system pressure limitation.
The shock valve is available with 280 bar [4061 psi] or 345 bar [5004 psi] setting.

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Part Options
For this option the high pressure port needs to be defined upfront to get the correct motor rotation.
Reversing the motor is not possible with this option.
Flow direction
Motor shaft rotation (asseen from shaft side)

Port APort B

System Port type, Loop
Flushing & Anticavitation*

Clockwise (CW)

Out

In

MD1/MD2/SD1/SD2

Counterclockwise (CCW)

In

Out

MC1/MC2/SC1/SC2* See Master Model Code in Technical Information, BC290322888218

Anti cavitation and shock valve, Port B High Pressure, Clockwise rotation
L2

N

A

CW

B

Shock valve

Anti-cavitation valve

L1
P400636

Anti-cavitationand shock valve

P400658

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Part Options
Anti cavitation and shock valve, Port A High Pressure, Counter Clockwise rotation
L2

N

A

CCW

B
L1
P400635

Anti-cavitationand shock valve

P400660

Speed and Temperature Sensor
MP1 motors are available with an optional speed and temperature sensor. This hall-effect pulse pick-up islocated in the motor housing. The sensor accepts supply voltage and outputs a digital pulse signal in
response to the speed of the cylinder block. The output changes its high/low state as the target teeth
pass by the sensor's face. The digital (on-off-on-off) pulse train is fed to a controller, which interprets its
rate of change as a speed. A logic circuit decodes the two signals to provide an additional direction
indication (high or low) depending on direction).
The speed sensor is designed for rugged outdoor, mobile or heavy industrial speed sensing applications.
The detection of the speed is contactless and does not need any calibration or adjustments. There are
two optional sensors available.
Available Sensors
Description© Danfoss | April 2023

Order number
14905511232698

Supply voltage

4.5 – 8 V

7 – 32 V

Speed signals

Two, 90° Phase shiftTwo, 90° Phase shift

Direction signal

One

One

Temperature signal

One

One

PLUS+1 Compliance

Yes

No

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MP1 Motor
Part Options
Sensor Position
Sensor position in SAE and Cartridge housing.
SAE & Cartridge housing

Speed sensor
protection
Speed sensor

Grooves on
cylinder blockP400649

Sensor target
Nine arc grooves on cylinder block as target of sensor for detection of direction (CW/CCW) and rotation.
Speed Sensor 4.5 - 8 V
Pinout:1. Speed signal 2
2. Direction signal
3. Speed signal 1
4. Supply
5. Ground
6. Temperature

Speed sensor connector, 6-pin
4 56
3 2 1
P006035

Technical data

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Parameter

Min.

Nom.

Max.

Note

Supply voltage

4.5 VDC

5 VDC

8 VDC

Regulated supply voltage.
Reverse polarity protected.

Supply protection––

30 VDC

Shuts off above 9 V.

Pulses per revolution

NPN & PNP

Max. required supply current

–

–

25 mA

At supply voltage

Max. output current

–

–

50 mA

Operation mode

NPN & PNP

Temperature signal-40°C = 2.318V

Push-Pull amplifier–

100°C = 0.675V

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Part Options
Technical data (continued)
Parameter

Min.

Nom.

Max.

Note

Output low speed signal

5%

8.5 %

12 %

Ratiometric output voltage
Low state > 0 V to provide wire
fault detection

Output high speed signal

88 %91.5 %

95 %Detectable frequency range

1 Hz

–

10 000 Hz

Ordering number

149055

Color of connector

Black

Speed Sensor 7 - 32 V
Speed Sensor 7 – 32 VDC technical data and information about connector.
Pinout:1. Speed signal 2
2. Direction signal
3. Speed signal 1
4. Supply
5. Ground
6. Temperature signal

Speed sensor connector, 6-pin
4 56
3 2 1
P006035

Technical data
Parameter

Min.

Max.

Supply voltage range

7 VDC

32 VDC

Supply protection–

36 VDC

Max. required supply current

–

30 mA

Max. output current

–

50 mA

Operation mode

NPN open collector

Output low signal range

2%

10 %

Output high signal range

55 %

85 %

Detectable frequency range

1 Hz

10 000 Hz

Speed sensor order number

11232698

Color of connector

YellowNote

36 VDC over voltage protection-36 VDC permanent reverse
polarity protection

Internal 2k7 pull-up resistor to
supplyMax. output voltage 24 VDC

For more information, see Speed and Temperature Sensor, Technical Information, BC152886482203.
Output Pulses
The expected number of output pulses per revolution is shown below.
9

The number of pulses (per rev)

Due to the number of target groove (9) for pulse pick up, the output signal resolution is lower than otherproducts (e.g.71 target teeth for H1B-60) in extra low speed.
For more technical information, please contact your Danfoss representative.

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MP1 Motor
Operating Parameters
Overview
This section defines the operating parameters and limitations with regard to output speeds andpressures.
Speed Ratings
Smooth operation and output torque ripple determine the acceptable low speed operating condition.
Generally Danfoss axial piston motors will operate smoothly down to 150 rpm. In some instances, it ispossible to operate smoothly at less than 150 rpm, but performance must be verified for the specificapplication. We do not recommend that any axial piston motor be sized to operate continuously at
speeds less than 100 rpm.
Rated speed is the highest input speed recommended at full power condition. Operating at or below
this speed should yield satisfactory product life.
Maximum speed is the highest operating speed permitted. Exceeding maximum speed reduces productlife and can cause loss of hydrostatic power and braking capacity. Never exceed the maximum speed
limit under any operating conditions.
Operating conditions between Rated speed and Maximum speed should be restricted to less than fullpower and to limited periods of time. For most drive systems, maximum unit speed occurs during
downhill braking or negative power conditions.

W Warning
Unintended vehicle or machine movement hazard
The loss of hydrostatic drive line power, in any mode of operation (forward, neutral, or reverse) may cause
the system to lose hydrostatic braking capacity. You must provide a braking system, redundant to thehydrostatic transmission, sufficient to stop and hold the vehicle or machine in the event of hydrostatic
drive power loss.

System pressure
System pressure is the differential pressure between system ports A and B. It is the dominant operating
variable affecting hydraulic unit life. High system pressure, which results from high load, reduces
expected life. Hydraulic unit life depends on the speed and normal operating, or weighted average,pressure that can only be determined from a duty cycle analysis.
Application pressure is the high pressure relief setting normally defined within the order code of thepump. This is the applied system pressure at which the driveline generates the maximum calculated pullor torque in the application.
Maximum working pressure is the highest recommended Application pressure. Maximum working
pressure is not intended to be a continuous pressure. Propel systems with Application pressures at, or
below, this pressure should yield satisfactory unit life given proper component sizing.
Maximum pressure is the highest allowable Application pressure under any circumstance. Applicationpressures above Maximum Working Pressure will only be considered with duty cycle analysis and factory
approval. Pressure spikes are normal and must be considered when reviewing maximum working
pressure.
All pressure limits are differential pressures referenced to low loop (charge) pressure. Subtract low looppressure from gauge readings to compute the differential.
Minimum low loop pressure (above case pressure) is the lowest pressure allowed to maintain a safe
working condition in the low side of the loop.

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Operating Parameters
Case Pressure
Under normal operating conditions, the rated case pressure must not be exceeded. During cold start,case pressure must be kept below maximum intermittent case pressure. Size drain plumbing accordingly.

C Caution
Possible component damage or leakage.
Operation with case pressure in excess of stated limits may damage seals, and/or housings, causing
external leakage. Performance may also be affected since charge and system pressures are referenced tocase pressure.
Case pressure limits
Maximum (continuous)

2 bar [29 psi] maximum pressure

Intermittent (cold start)

6 bar [87 psi] maximum pressure

Temperature
The high temperature limits apply at the hottest point in the transmission, which is normally the motor
case drain. The system should generally be run at or below the published rated temperature.
The maximum intermittent temperature is based on material properties and should never be
exceeded.
Cold oil will generally not affect the durability of the transmission components, but it may affect theability of oil to flow and transmit power.
The minimum temperature relates to the physical properties of component materials.
Size heat exchangers too keep the fluid within these limits. Danfoss recommends testing to verify thatthese temperature limits are not exceeded.
Viscosity
Viscosity For maximum efficiency and bearing life, ensure the fluid viscosity remains in therecommended range.
The minimum viscosity should be encountered only during brief occasions of maximum ambient
temperature and severe duty cycle operation.
The maximum viscosity should be encountered only at cold start.
Ensure fluid temperature and viscosity limits are concurrently satisfied.

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MP1 Motor
Pressure Measurements
MP1M20/24 SAE A Flange Port Locations and Specifications
SAE A flange ports

System port A

System port B

Case drain port L1

Case drain port L2

Port information

20 | © Danfoss | April 2023

Port

Port size

Pressure obtained

Gauge size, bar [psi]L1, L2

3/4-16 UNF / M18 x 1.5

Case drain

10 [100]

A

7/8-14 UNF / M22 x 1.5

System pressure

500 [7250]

B

7/8-14 UNF / M22 x 1.5

System pressure

500 [7250]

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Service Manual
MP1 Motor
Pressure Measurements
MP1M20/24 SAE B Flange Port Locations and Specifications
SAE B flange ports

System port A

System port B

Case drain L1

Case drain port L2

Port information© Danfoss | April 2023

Port

Port size

Pressure obtained

Gauge size, bar [psi]L1, L2

3/4-16 UNF / M18 x 1.5

Case drain

10 [100]

A

7/8-14 UNF / M22 x 1.5

System pressure

500 [7250]

B

7/8-14 UNF / M22 x 1.5

System pressure

500 [7250]

AX323657269473en-000203 | 21

Service Manual
MP1 Motor
Pressure Measurements
MP1M20/24 Cartridge Flange Port Locations and Specifications
Cartridge flange ports

System port A

System port B

Case drain L1

Case drain port L2

Port information

22 | © Danfoss | April 2023

Port

Port size

Pressure obtained

Gauge size, bar [psi]L1, L2

3/4-16 UNF / M18 x 1.5

Case drain

10 [100]

A

7/8-14 UNF / M22 x 1.5

System pressure

500 [7250]

B

7/8-14 UNF / M22 x 1.5

System pressure

500 [7250]

AX323657269473en-000203

Service Manual
MP1 Motor
Pressure Measurements
MP1M28/32 SAE B Flange Port Locations and Specifications
SAE B flange ports

System port A

System port B

Case drain L1

Case drain port L2

P400781

Port information© Danfoss | April 2023

Port

Port size

Pressure obtained

Gauge size, bar [psi]L1, L2

3/4-16 UNF / M18 x 1.5

Case drain

10 [100]

A

1-1/16 -12 UNF / M27x2

System pressure

500 [7250]

B

1-1/16 -12 UNF / M27x2

System pressure

500 [7250]

AX323657269473en-000203 | 23

Service Manual
MP1 Motor
Pressure Measurements
MP1M28/32 Cartridge Flange Port Locations and Specifications
Cartridge flange ports

System port A

System port B

Case drain port L1

Case drain port L2
P400782

Port information

24 | © Danfoss | April 2023

Port

Port size

Pressure obtained

Gauge size, bar [psi]L1, L2

3/4-16 UNF / M18 x 1.5

Case drain

10 [100]

A

1-1/16 -12 UNF / M27x2

System pressure

500 [7250]

B

1-1/16 -12 UNF / M27x2

System pressure

500 [7250]

AX323657269473en-000203

Service Manual
MP1 Motor
Fluid and Filter Maintenance
Recommendations of Fluid and Filter MaintenanceTo ensure optimal product life, perform regular maintenance of the fluid and filter. Contaminated fluid is
the main cause of unit failure. Take care to maintain fluid cleanliness when servicing.
Check the reservoir daily for proper fluid level, the presence of water, and rancid fluid odor. Water in thefluid may be noted by a cloudy or milky appearance or free water in the bottom of the reservoir. Rancid
odor indicates the fluid has been exposed to excessive heat. Change the fluid immediately if these
conditions occur. Correct the problem immediately.
Inspect vehicle for leaks daily.
Change the fluid and filter per the vehicle / machine manufacturer’s recommendations or at theseintervals: Change the fluid more frequently if it becomes contaminated with foreign matter (dirt, water,
grease, etc.) or if the fluid is subjected to temperature levels greater that the recommended maximum.
Fluid and filter change interval
Reservoir type

Maximum change interval

Sealed2000 hours

Breather

500 hours

C Caution
High temperatures and pressures accelerate fluid aging. These conditions will require more frequent fluidchanges.
Change filters whenever the fluid is changed or when the filter indicator shows that it is necessary tochange the filter. Replace all fluid lost during filter change.

W Warning
Hydraulic fluid contains hazardous material. Avoid contact with hydraulic fluid. Always dispose of usedhydraulic fluid according to state, and federal environmental regulations. Never reuse hydraulic fluid.

© Danfoss | April 2023

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Service Manual
MP1 Motor
Initial Start-Up ProceduresStart-up Safety Precautions
This service procedure may require disabling the vehicle / machine (raising the wheels off the ground,
disconnecting work function). Take the necessary safety precautions to prevent injury to the technician
and bystanders.

W Warning
Unintended vehicle/machine movement may occur when using the motor in combination with S45 open
circuit pumps with LS, EPC, or FDC controls and the engine is turning.
Due to the design of these controls, a standby pressure will remain in the system even if the normallyclosed control are fully energized. Lowest standby pressures to the motor, 12-18 bar or above, may beenough to turn the motor and has the potential to cause injury or damage.
The initial start-up procedure must be completed in order: inspect the unit, fill system components withhydraulic fluid, install charge pressure gauge and calibrate the motor/transmission.
Inspect the Unit
1. Before installing the motor, inspect the units for possible damage incurred during shipping andhandling.
2. Make certain all system components (reservoir, hoses, valves, fittings, heat exchanger, etc.) are clean
before filling with fluid. Never reuse hydraulic fluid.
Fill System Components with Hydraulic Fluid
1. Fill the reservoir with recommended hydraulic fluid. Pass this fluid through a 10 micron (nominal, no
bypass) filter before it enters the reservoir.
2. Fill the inlet line leading from the reservoir to the pump. Check the inlet line for properly tightened
fittings and be certain it is free of restrictions and air leaks.
3. Check inlet line for properly tightened fittings. Make sure the inlet line is free of restrictions and airleaks.
4. Fill the motor and pump housings with clean hydraulic fluid before start up. Fill by pouring filtered oil
into the upper case drain port. To ensure the pump and motor stay filled with oil, install case drainlines into the upper most case drain ports.
Attention
Never start the prime mover unless the motor and pump housings are filled completely with clean
hydraulic fluid.

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Service Manual
MP1 Motor
Initial Start-Up Procedures
Install Charge Pressure Gauge
1. For closed loop systems, install a 0-35 bar [0-500 psi] pressure gauge in the charge pressure gauge
port of the pump to monitor the charge pressure during start-up.
For open circuit systems, use gauges in system ports.
2. Disconnect any external control input signal or command from the pump control until after initialstart-up. This ensures that the pump remains in its neutral position.
3. Jog (slowly rotate) prime mover until charge pressure starts to rise.
4. Start the prime mover and run at the lowest possible speed until charge pressure builds.

W Warning
Do not start the prime mover unless the pump is in neutral position (swash plate at 0° angle). Take
necessary precautions to prevent machine movement in case pump is actuated (in stroke) duringinitial start-up.
5. Once charge pressure is established, increase to normal operating speed. Charge pressure should be
as indicated in the pump model code. If charge pressure is low, shut down and determine cause.

C Caution
Low charge pressure may affect ability to control the machine.
Calibrate the Motor/Transmission
1. Shut down the prime mover.
2. Connect the external control input signal/command.
3. Reconnect the machine function if disconnected earlier.
4. Start the prime mover, checking to ensure the pump remains in neutral.
5. Check for forward and reverse machine operation, with the prime mover at normal operating speed.
Charge pressure may decrease slightly during forward or reverse operation.
6. Continue to cycle slowly between forward and reverse for at least five minutes.
7. Shut down prime mover.
8. Remove gauges. Replace plugs at the gauge ports.
9. Check reservoir level. Add filtered fluid if needed.
The motor/transmission is now ready for operation.

© Danfoss | April 2023

AX323657269473en-000203 | 27

Service Manual
MP1 Motor
Troubleshooting
Troubleshooting Overview
This section serves as a guide for identifying and resolving undesirable system conditions.
Please observe the safety concerns listed in Safety Precautions on page 5 and the precautions related to
relevant equipment when resolving system issues.
System Operating Hot
Item

Description

ActionCheck oil level inInsufficient amount of hydraulic fluid will not meet the cooling demands of Fill the reservoir to the proper level.
reservoir and oil supply the system.
to the pump.
Inspect the heatexchanger (ifequipped).

If the heat exchanger fails or becomes obstructed, it may not meet thecooling demands of the system.

Ensure that heat exchanger is receiving adequate
air flow and that the heat exchanger is in good
operating condition. Repair or replace asnecessary.

Check the system relief
valves.

If a system relief valve becomes unseated for an extended period of time or Repair or replace any malfunctioning relief valvesfails for any other reason, the system could become overheated.
as applicable and verify that the lads on themachine are not excessive.

System Noise or Vibration
Item

Description

ActionCheck oil level inInsufficient hydraulic fluid could lead to cavitation that would cause
reservoir and oil supply system noise.
to the motor.

Fill the reservoir to the proper level and ensurethat oil supply to the motor is adequate and thelines are unobstructed.

Check for air in thesystem.

Air trapped within the system lines or the motor itself could result incavitation that would cause system noise.

Ensure that all of the system lines andcomponents are purged of air.

Inspect the output
shaft couplings.

A loose or incorrect shaft coupling will produce vibrations that could result Ensure that the correct coupling is used and thatin system noise.
it fits properly onto the shaft.

Inspect the output
shaft alignment.

Misaligned shafts create excessive frictional vibration that could result insystem noise.

Hydraulic oil viscosity
about limits.

Viscosity above acceptable limits will result in cavitation that would lead to Replace hydraulic oil with appropriate fluid forsystem noise.
operating conditions. Refer to publication
5200L0463 for information on fluid selection.

28 | © Danfoss | April 2023

Ensure that the shafts are properly aligned.

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Service Manual
MP1 Motor
Minor Repair
Shaft Seal and Dust Seal
MP1M shaft seal and dust seal removal
1. Orient the motor with the shaft pointing upward.
2. If a dust seal is used, use snap ring pliers to remove retaining ring (D210) retaining the dust seal.
3. If a dust seal is used, remove the dust seal (D200).
4. Using snap ring pliers, remove retaining ring (D150) retaining the shaft seal and support washer.
5. Remove support washer (D140).
6. Remove shaft seal (D130) and discard.

C Caution
Do not damage the housing bore, shaft or bearing when removing the shaft and shaft seal.
Carefully drive a small sheet-metal screw into the shaft seal to facilitate removal. Be careful not todamage the bearing below the seal. Attach a slide hammer or appropriate puller to the screw headand pull to remove the seal.
D210

D200

D150
D140
D130

© Danfoss | April 2023

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Service Manual
MP1 Motor
Minor Repair
MP1M Shaft Seal and Dust Seal Assembly
1. Inspect the new seal, the motor housing seal bore, and the sealing area on the shaft for rust, wear,
and contamination. Polish the shaft and clean the housing if necessary.
2. Position the motor with the shaft pointing upward.
3. Install the retaining ring (D120) using snap ring pliers.
The retainer ring (D120) is beveled and has a direction requirement; the flat side of the retainer ringmust face the bearing.
4. Cover shaft splines with an installation sleeve or packaging tape to protect seal during installation.
Lubricate new shaft seal (D130), press into housing until it bottoms out. Press evenly to avoid binding
and damaging the seal.

C Caution
Do not damage the housing bore or shaft when replacing the shaft seal. All components should fit
together smoothly.
5. Install support washer (D140).
6. Using snap ring pliers, install the retaining ring (D150) that retains the support washer and shaft seal.

C Caution
Do not swap retainer rings D120 and D150.
7. If a dust seal is used, install dust seal (D200).
8. If a dust seal is used, use snap ring pliers to install the retaining ring (D210) to retain the dust seal.
D210
*D200
D150
D140
*D130
D120

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Service Manual
MP1 Motor
Minor Repair
Speed Sensor
MP1M Speed Sensor Removal
1. Using a 5mm internal hex wrench, remove screw (K310).
2. Remove speed sensor cover (K350), if used.
3. Remove speed sensor (K300).
4. Discard O-ring (QK301).
K310
K350

K300
K310
K300
K310
QK301
K300

QK301

QK301

MP1M Speed Sensor Assembly
1. Lubricate and install new O-ring (QK301).
2. Install speed sensor (K300).
3. Install speed sensor cover (K350), if used.
4. Install screw (K310) using a 5 mm internal hex wrench with torque to 8 N•m [71 lbf•in].

© Danfoss | April 2023

AX323657269473en-000203 | 31

Service Manual
MP1 Motor
Minor Repair
Loop Flushing Valve
MP1M Loop Flushing Valve Removal
1. Using a 19 mm or 3/4 in wrench, remove plugs (E400) and (E410).
2. Remove and discard O-rings (with plugs E400 and E410).
3. Using pliers, remove centering springs (E210 and E260).
4. Remove spring seats (E220 and E270).
5. Remove shift spool (E200).

E400
E210
E220

E100
E200
E270
E260
E410

MP1M Inspect the Components
Inspect sealing area for rust, wear, or contamination. Also check springs for wear.
MP1M Install the Loop Flushing Valve
1. Install shift spool (E200).
2. Install spring seats (E220 and E270).
3. Carefully install centering springs (E210 and E260).
4. Install new O-rings for plugs (E400 and E410).
5. Using a 19 mm or 3/4 in wrench, torque plugs (E400 and E410) to 35 N•m [310 lbf•in].

32 | © Danfoss | April 2023

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Service Manual
MP1 Motor
Minor Repair
Anti-cavitation Valve
MP1M Remove the Anti-cavitation Valve (Supply Check Relief Valve)
1. Using a 22 mm wrench, remove plugs (E400) and (E410).
2. Remove and discard O-rings (with plugs E400 and E410).
3. Using pliers, carefully remove conical spring (E310). This spring will be on the same side as the supply
check relief valve. Please note the direction in which the spring was installed.
4. Carefully remove supply check relief valve assembly (E300). Depending on the configuration selected,
this valve may be on the A or B port side. Please note the direction in which this valve was installed.
MP1M Inspect the Components
Inspect sealing area for rust, wear, or contamination. Also check springs for wear.
MP1M Install the Anti-cavitation Valve
1. Install the plug (either E400 or E410) and a new O-ring on the opposite side of where the anticavitation valve will be installed using a 22 mm wrench. Torque to 78 N•m [690 lbf•in].
2. Install the supply check relief valve (E300) on the desired port side. Please note the original directionin which this valve was installed.
3. Carefully install conical spring (E310). Please note the direction in which the spring was installed.
4. Install the plug (either E400 or E410) and a new O-ring on the same side as the supply check relief
valve using a 22 mm wrench. Torque to 78 N•m [690 lbf•in].

E400
E310
E300
Option codes:
SC1, SC2, MC1, MC2

E350
E360
Option codes:
SD1, SD2, MD1, MD2© Danfoss | April 2023

E410

AX323657269473en-000203 | 33

Service Manual
MP1 Motor
Torque Chart
MP1M Fasteners and Torque34 | © Danfoss | April 2023

Item

Fastener

Torque

K310

Screw

8 N•m [71 lbf•in]

E400 and E410 (loop flushing)Plug

35 N•m [310 lbf•in]

E400 and E410 (anti-cavitation)

Plug

78 N•m [690 lbf•in]

AX323657269473en-000203

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Danfoss Power Solutions is a global manufacturer and supplier of high-quality hydraulic andelectric components. We specialize in providing state-of-the-art technology and solutions
that excel in the harsh operating conditions of the mobile off-highway market as well as themarine sector. Building on our extensive applications expertise, we work closely with you toensure exceptional performance for a broad range of applications. We help you and othercustomers around the world speed up system development, reduce costs and bring vehicles
and vessels to market faster.

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Danfoss Power Solutions – your strongest partner in mobile hydraulics and mobile
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Go to www.danfoss.com for further product information.

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We offer you expert worldwide support for ensuring the best possible solutions foroutstanding performance. And with an extensive network of Global Service Partners, we also
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www.hydro-gear.com
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Phone: +1 515 239 6000

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Krokamp 35
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All trademarks in this material are property of the respective companies. Danfoss and the Danfoss logotype are trademarks of Danfoss A/S. All rights reserved.

© Danfoss | April 2023

AX323657269473en-000203