Overview
This manual includes information for the installation, maintenance, and minor repair of H1 tandem
pumps. It includes a description of the unit and its individual components, troubleshooting information,
and minor repair procedures.
Performing minor repairs requires the unit to be removed from the vehicle/machine. Thoroughly clean
the unit before beginning maintenance or repair activities. Since dirt and contamination are the greatest
enemies of any type of hydraulic equipment, follow cleanliness requirements strictly. This is especially
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 and
certifies Global Service Partners on a regular basis. You can locate your nearest Global Service Partner
using the distributor locator at
http://www.powersolutions.danfoss.com
.
Warranty
Performing adjustments and minor repairs according to the procedures in this manual will not affect your
warranty. Major repairs requiring the removal of a unit’s center section, servo sleeves, or front flange
voids the warranty unless a Danfoss Authorized Service Center performs them.
General instructions
Follow these general procedures when repairing this product.
Remove the unit
If necessary, remove the unit from the vehicle/machine. Chock the wheels on the vehicle or lock the
mechanism to inhibit movement. Be aware that hydraulic fluid may be under high pressure and/or hot.
Inspect the outside of the pump and fittings for damage. Cap hoses after removal to prevent
contamination.
Keep it clean
Cleanliness is a primary means of assuring satisfactory pump life, on either new or repaired units. Clean
the outside of the pump thoroughly before disassembly. Take care to avoid contamination of the system
ports. Cleaning parts by using a clean solvent wash and air drying is usually adequate.
As with any precision equipment, keep all parts free of foreign materials and chemicals. Protect all
exposed sealing surfaces and open cavities from damage and foreign material. If left unattended, cover
the pump with a protective layer of plastic.
Replace all O-rings and gaskets
Danfoss recommends that you replace all O-rings, seals and gaskets. Lightly lubricate all O-rings with
clean petroleum jelly prior to assembly.
Secure the unit
For repair, place the unit in a stable position with the shaft pointing downward. It will be necessary to
secure the pump while removing and torquing end covers, controls, and valves.
Service Manual
H1 45/53/60/68 Tandem Closed Circuit Axial Piston Pumps
Introduction
©
Danfoss | June 2018
520L0928 | AX00000103en-US0303 | 5